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Biomedical subjects

P J Thomson

Publications and source records attributed to P J Thomson.

14 recordsLinked to original sources
PubMed1999

Tritiated thymidine and bromodeoxyuridine double-labelling studies on growth factors and oral epithelial proliferation in the mouse.

Mouse tongue epithelium is characterized by a circadian variation in the number of cells undergoing DNA synthesis. Groups of male BDF1 mice were followed over 48 h and a double-labelling method with tritiated thymidine and bromodeoxyuridine used to determine S-phase labelling indices, together with cell influx to and cell efflux from S, at 4-hourly time points. Control animals exhibited diurnal peaks in labelling index at 03:00 with trough activity 12 h later at 15:00. Cell influx peaked at 23:00 with troughs occurring between 11:00 to 15:00. Peak cell efflux occurred at 07:00 with trough activity at 19:00. Animals injected with epidermal growth factor at 05:00 demonstrated a significant fall in both influx and efflux throughout the 48-h period (P < 0.001), but with preservation of labelling indices, suggesting a slower transit of cells through S-phase, whereas epidermal growth factor injected at 15:00 only produced a significant rise in cell-efflux values. Adrenergic stimulation by intravenous phenylephrine/isoprenaline injection at both 05:00 and 15:00 resulted in a significant rise in cell efflux (P < 0.001), although there was also a rise in labelling index in the 15:00 group (P < 0.001). Animals injected with calmodulin at 05:00 demonstrated a significant reduction in labelling index throughout the 48-h period (P < 0.001), but maintained control values for cell influx and efflux, suggesting faster transit of cells through S. Calmodulin injection at 15:00 produced only a significant reduction in cell influx (P < 0.001). Administration of exogenous growth factors significantly alters the normal rhythmical proliferation of oral epithelial cells in a mouse model. These effects appear to be both growth factor- and time-dependent, and may have both physiological and pathological implications.

Adrenergic alpha-Agonists↗
PubMed1997

Preoperative vascular assessment: an aid to radial forearm surgery.

Twenty-three patients undergoing oral reconstructive surgery with radial forearm free flaps had a vascular assessment of the forearm preoperatively. Segmental upper limb pressures were measured and colour flow duplex visualization of forearm vessels and blood flow done. In 18 the blood pressure and flow were within normal limits, but five (22%) showed either unilateral or bilateral arteriopathy or aberrant vascular anatomy. Identification of pre-existing vascular disease helps to rationalize the selection of donor vessels, reduces the risk of ischaemic damage to the hand after disruption of the radial artery and may be of benefit in reducing the incidence of failure of free flaps.

Adult↗
PubMed1996

Persistent haemorrhage following dental extractions in patients with liver disease: two cautionary tales.

Two cases are reported in which patients known to suffer from chronic liver disorders underwent local anaesthetic dental extractions. In both cases the procedure was followed by severe, intractable post-operative haemorrhage, resistant to local haemostatic measures and requiring hospital admission for intravenous fluid replacement and administration of clotting factors. The importance of not only eliciting details of a patient's medical history, but also of acting appropriately upon that information is emphasised and a recommendation is made that patients with active liver disorders, such as cirrhosis, who require oral surgery procedures should be managed in hospital departments, where access to haematological assessment and appropriate surgical and medical care is readily available. Close liaison with liver physicians and haematologists is recommended.

Adult↗
PubMed1996

Auditing clinical teaching in oral surgery: the use of a student log book.

Objective assessments of clinical teaching are difficult; in oral surgery students must acquire a wide range of clinical and operative skills before qualifying as independent dental practitioners. A student log book system was introduced in Manchester University to monitor student progress and assess the efficacy of clinical instruction in oral and maxillofacial surgery following the introduction of the new 5-year BDS curriculum. Initial appraisal of third- and fourth year students undertaking 10-week clinical attachments revealed generally high levels of attendance (greater than 80%), and reasonable clinical experience (over 80% of students acquiring regular experience of dentoalveolar surgery and extractions). However, individual variation in both attendance and achievement was wide, and a persistent 8% of students did not appear to gain any practical experience. Students achieving less than the average course performance marks were thus easily identified and measures initiated to identify and correct their difficulties. Log book assessment also facilitated effective audit of teaching staff, clinical sessions and overall course delivery. The use of student log books to record clinical performance is recommended as a versatile aid to clinical teaching practice.

Documentation↗
PubMed1995

Mental nerve dysfunction: a symptom of diverse mandibular disease.

Paraesthesia and anaesthesia of the mental nerve may result from a variety of pathological conditions, and in persistent cases of orofacial sensory disturbance thorough clinical assessment, including CT scanning, is vital to exclude underlying systemic or neoplastic disease. This paper presents three patients with right mental nerve dysfunction, and reviews the aetiology of mental nerve paraesthesia and anaesthesia.

Adult↗
PubMed1993

Recovery from intravenous sedation with midazolam--the value of flumazenil.

A total of 40 patients receiving intravenous midazolam for surgical removal of impacted wisdom teeth were randomly assigned to recover either spontaneously or undergo reversal by the benzodiazepine antagonist flumazenil. Whilst initial postoperative recovery to a 'fully awake' state occurred more rapidly in the reversal group, objective psychomotor testing revealed significantly poorer performance postoperatively compared with spontaneously recovering patients; this emphasises the need to retain patients for at least 1 h prior to discharge home.

Adult↗
PubMed1993

Statistical discriminant analysis of arrhythmias using intracardial electrograms.

The problem of classifying ventricular arrhythmias from intracardial electrograms is considered. Standard statistical discrimination procedures are applied using a simple parametric model for the shape of the pulse near its peak. This approach makes simultaneous use of the model parameters, has well known statistical properties, and involves computations that can be carried out efficiently. Preliminary analyses of real data sets, using both linear and quadratic discrimination functions, yield promising results.

Algorithms↗
PubMed1991

Cancelled operations. A current problem in oral and maxillofacial surgery.

Public concern has recently focused on the problem of cancelled operations. In order to investigate the extent of oral and maxillofacial surgery cancellations, the University of Manchester initiated a 12-month prospective audit of lost operating time. During 1990, 31% of planned operations were cancelled, while nearly 20% of operating lists were lost completely. With the exception of public holidays and theatre maintenance days, the commonest reasons for cancellation included financial cut-backs, nursing staff shortages and failure of patients to attend.

Appointments and Schedules↗
PubMed1991

Reducing failure rates for in-patient oral surgery. The use of a pre-admission clinic.

A large proportion of oral and maxillofacial surgery operations are non-urgent, elective procedures. Approximately 30% of patients called for operation from routine waiting lists consistently fail to attend, thus leading to inefficient bed utilisation and wastage of theatre time. In an attempt to reduce patient failure rates and to investigate reasons for non-attendance, the Department of Oral and Maxillofacial Surgery developed a new pre-admission clinic; admission dates for in-patient surgery are only arranged following successful attendance and satisfactory 'clerking in' at the pre-admission clinic. Over an initial 5-month period, in-patient attendance rates increased to 87% and, at the same time, validation of waiting lists was facilitated, with nearly three-quarters of clinic non-attenders eventually being removed from the lists. The pre-admission clinic thus appears to offer a useful and versatile approach towards more efficient in-patient management.

Admitting Department, Hospital↗
PubMed1991

A central venous catheter complicating head and neck surgery.

A case is reported of a central venous catheter that was placed inadvertently into the internal jugular vein during the anaesthetic preparation for surgery. The catheter tip was sectioned during surgery and was feared to have embolised into the central circulation but it was subsequently identified in the pathological specimen. A summary of the complications associated with central venous catheterisation is reported and a simple protocol is proposed to avoid a similar complication.

Aged↗
PubMed1991

Changes in oxygen saturation using two different sedation techniques.

Pulse oximetry was used to assess the degree of hypoxia observed in patients receiving simple midazolam sedation for removal of lower third molars and compared to that seen in patients receiving a combination sedation technique using nalbuphine and midazolam. Results showed that the degree of hypoxia experienced by patients receiving the combination technique was significantly more profound in both incidence and depth than that seen in the group receiving midazolam alone (p less than 0.05).

Procedural Sedation↗
PubMed1967

The effects of sodium ions and potassium ions on glycine uptake by mouse ascites-tumour cells in the presence and absence of selected metabolic inhibitors.

1. The initial rate, v, of glycine uptake by ascites-tumour cells respiring their endogenous nutrient reserves was studied as a function of the respective extracellular concentrations of glycine, Na(+) and K(+). With the extracellular concentration of Na(+)+K(+) constant at 158m-equiv./l. and that of glycine either 4 or 12mm, v tended to zero as the extracellular concentration of Na(+) approached zero. Glycine appeared to enter the cells as a ternary complex with a carrier and Na(+). K(+) competed with Na(+) for one of the carrier sites, whereas glycine was bound at a second site. The values of the five relevant binding constants showed that the two sites interacted. 2. The glycine uptake rate at various extracellular concentrations of glycine and Na(+) was scarcely affected by starving the cells for 30min. in the presence of 2mm-sodium cyanide provided that cellular Na(+) and K(+) contents were kept at the normal values. When the cells took up Na(+), however, v decreased approximately threefold. 3. When their Na(+) content was relatively small and the extracellular concentration of Na(+) was large, the starved cells accumulated glycine in the presence of cyanide for about 15min. Glycine then tended to leave the cells. An average of about 5mumoles of glycine/ml. of cell water was taken up from a 1mm solution, representing about 20% of the accumulation observed during respiration. Studies with fluoride, 2,4-dinitrophenol and other metabolic inhibitors supported the view that ATP and similar compounds were not implicated. The relation between the transient accumulation of glycine that occurred in these circumstances and the normal mode of active transport was not established.

Adenosine Triphosphate↗