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Biomedical subjects

M F James

Publications and source records attributed to M F James.

At least 73 records · Page 4Linked to original sources
PubMed1995

Joint space measurement in hand radiographs using computerized image analysis.

OBJECTIVE: To compare computerized joint space (JS) measurements with conventional joint space narrowing (JSN) scores in patients with mild rheumatoid arthritis. METHODS: Serial paired hand and wrist radiographs from 34 patients with classic rheumatoid arthritis were evaluated. Purpose-written software automatically measured the JS on test images and standard clinical hand radiographs; JSN was scored "blind" by 6 observers. RESULTS: The software proved reliable. JS values differed significantly (men > women; metacarpophalangeal > proximal interphalangeal joints), declining with disease duration more than with age; JSN scores correlated poorly and varied more. CONCLUSION: Computerization permits sensitive JS measurement and should be of benefit in studies of early joint disease.

Adult↗
PubMed1995

Visualisation of subchondral erosion in rat monoarticular arthritis by magnetic resonance imaging.

High-resolution magnetic resonance imaging (MRI) was used to investigate antigen-induced monoarticular arthritis (AIMA) in the rat. In sagittal, spin-echo images of the knee, characteristic parallel bands, in the order dark-light-dark, were consistently observed 5-8 days after arthritis induction; the bands ran concentric with, and just beneath, the femoral and tibial articular surfaces. Concurrent radiology, histology and MRI (chemical shift-selective imaging and contrast enhancement with magnetisation transfer and gadolinium) established that the phenomenon reflected subchondral erosion, not artefact. The outer hypointense band corresponded to calcified cartilage underlying the articular surface. The central hyperintense band reflected inflammatory matrix displacing normal haematopoietic tissue immediately subchondrally; here, trabecular bone had mostly disappeared, but adjacent articular cartilage, although under attack and lacking proteoglycan, appeared structurally normal. The inner hypointense band reflected deeper, truncated trabeculae within inflammatory matrix, layered with pallisading osteoblast-like cells. This study exemplifies the power of MRI for revealing localised joint pathology non-invasively, and shows that rat AIMA shares many pathological features with arthritis in human beings.

Animals↗
PubMed1995

Effect of magnesium on coagulation as measured by thrombelastography.

Magnesium has long been assumed to have anticoagulant properties, but the effect has been poorly quantified. The thrombelastograph (TEG) was used to evaluate the effect of magnesium using blood from volunteers. Magnesium sulphate was added to one blood sample and another sample was used as a control. Both samples were tested simultaneously and the results evaluated against the magnesium concentration measured in each sample. At serum magnesium concentrations < 3 mmol litre-1, there were no significant effects of magnesium. With increasing magnesium concentrations there was a statistically significant but small prolongation of the r time, k time and r + k time. Maximum amplitude was affected only at magnesium concentrations > 7 mmol litre-1. Magnesium has only minimal effects on coagulation which are unlikely to be clinically important.

Blood Coagulation↗
PubMed1995

Total i.v. anaesthesia with propofol and the laryngeal mask for orthopaedic surgery.

One hundred ASA I orthopaedic surgical patients (four randomized groups) were anaesthetized using continuous propofol and intermittent fentanyl (TIVA), with controlled ventilation via a tracheal tube in groups 1 and 2, and a laryngeal mask airway (LMA) in groups 3 and 4. Neuromuscular blockers were used in groups 1 and 3 only. There were no significant differences between groups in total anaesthetic requirements, as assessed by cardiovascular variables and movement. Coughing interfered with surgery and made controlled ventilation difficult to manage. In contrast, movement not associated with coughing did not impair surgery or ventilation. Patients in group 2 (tracheal tube, no neuromuscular blocker) required more interventions for coughing than the other groups, while patients in group 4 (LMA, no neuromuscular blocker) needed more boluses for movement than groups 1 and 3. Groups 1 and 2 (tracheal tube) had significantly higher heart rates and mean arterial pressures than groups 3 and 4 for varying periods up to 5 min after insertion of the airway management device. There was no correlation between mean arterial pressure and plasma concentrations of catecholamines related to insertion of either the tracheal tube or LMA. The LMA was found to be a highly effective device for controlled ventilation in TIVA and easier to manage than the tracheal tube in the absence of neuromuscular blockers.

Adolescent↗
PubMed1995

A prospective study of anaesthesia for quinsy tonsillectomy.

A prospective study of 50 adult quinsy tonsillectomy anaesthetics was performed. There were no significant anaesthetic or surgical complications and the mean intra-operative blood loss was 176 ml. The Mallampati score did not correlate with the Cormack and Lehane glottic view and there were no difficult intubations. Pre-operative trismus resolved completely during induction in 77.4% of cases. We concluded that the Mallampati grading system is not applicable in quinsies and in cases with palatopharyngeal arch distortion, that trismus in quinsies is due to muscle spasm and resolves completely during induction in most cases and that pre-anaesthetic drainage of the abscess together with rehydration and antibiotics are important contributing factors to safe anaesthesia for quinsy.

Adolescent↗
PubMed1994

High-resolution magnetic resonance imaging of arthritic pathology in the rat knee.

High-resolution magnetic resonance imaging (MRI) has been used to visualise the changes that occur in both soft tissue and bone during antigen-induced, monoarticular arthritis (AIMA) of the rat knee. Extensive optimisation studies were performed in order to minimise the time of the experiments and to maximise both the signal-to-noise ratio and the contrast in the MR images. The study was cross-sectional rather than longitudinal and at each of the 13 time points studied during the progression of the disease, corresponding X-radiographs and histological sections were obtained. Interpretation of the spin echo MR images was aided by the use of chemical shift-selective imaging, magnetisation transfer contrast and relaxation time experiments, as well as by correlation with the histology and X-radiography data. The MR images clearly show invasion of the synovium by an inflammatory pannus which spreads over the articular cartilage and invades the bone, leading to erosion and later remodelling. Two distinct types of bony erosion were observed: focal erosions, especially at the margins of the joint, and subchondral erosions. It is concluded that MRI provides a sensitive, non-invasive method for investigating both early-stage inflammatory changes and late-stage bony changes in the knee joints of the arthritic rat.

Animals↗
PubMed1994

Spinal anaesthesia but not general anaesthesia enhances neutrophil biocidal activity in hip arthroplasty patients.

The purpose of this study was to compare neutrophil cidal activity during general or spinal anaesthesia. Assays were performed on neutrophils extracted from the blood of patients after surgery had been under way for one hour. First, the ability of the neutrophils to kill a standard laboratory strain of S. aureus was examined. Neutrophils extracted from the blood during surgery in the spinal anaesthetic group and incubated with the staphylococci for one hour killed twice as many bacteria than those from two groups of patients that received halothane or isoflurane general anaesthesia (P < 0.05). This effect persisted, to a lesser extent, in the spinal group neutrophils after two hours of incubation with the bacteria. Second, neutrophils from patients under the same conditions of surgery and anaesthesia were tested to examine the effect of the different anaesthetic techniques on neutrophil biocidal mechanisms. Neutrophils extracted during surgery in the spinal group released more superoxide in response to phorbol-12-myristate-13-acetate (PMA) than those from both groups of patients that received general anaesthesia (P < 0.05). It is concluded that there is an increased state of reactivity of the neutrophil cell membrane NADPH oxidase system in patients receiving spinal anaesthesia than in patients receiving general anaesthesia.

Adult↗
PubMed1994

Haemodynamic and catecholamine changes after induction of anaesthesia with either thiopentone or propofol with suxamethonium.

We have compared the haemodynamic and catecholamine responses to laryngoscopy and tracheal intubation in 43 patients after induction of anaesthesia with either thiopentone 5.1 (SD 0.9) mg kg-1 or propofol 2.2 (0.1) mg kg-1, each with suxamethonium and without opioid pretreatment. Heart rate increased significantly above baseline after induction and intubation in both groups, but there were no differences between groups. Arterial pressure increased significantly at 1 min after intubation in both groups and at 2 min in the thiopentone group only. Plasma concentrations of adrenaline increased significantly compared with concentrations before induction, 1 min after intubation in both groups and at 2 min in the thiopentone group only. Plasma concentrations of adrenaline were significantly greater in the thiopentone group than in the propofol group at both 1 and 2 min after intubation. Plasma concentrations of noradrenaline showed no significant time-based within-group changes, but were significantly greater in the thiopentone group at 1 and 2 min after intubation. We conclude that doses of either thiopentone or propofol sufficient to obtund the eyelash reflex with suxamethonium 1 mg kg-1 alone do not adequately block the catecholamine and hypertensive responses to laryngoscopy and intubation in normal patients and although propofol suppressed increases in catecholamines to a greater extent than thiopentone, there were no clinical advantages.

Adolescent↗
PubMed1993

The effects of inhibition of plasma cholinesterase activity on systemic toxicity and blood catecholamine levels from cocaine infusion in pigs.

We investigated systemic effects and possible mechanisms for lethality of intravenously infused cocaine in spontaneously breathing and mechanically ventilated unconscious Landrace male pigs weighing about 26 kg (25.75 +/- 0.25 kg) that were pretreated with either saline solution (groups 1 and 3) or iso-ompa (tetraisopropyl pyrophosphoramide), a specific plasma cholinesterase inhibitor (groups 2 and 4). Pigs were made unconscious with sodium thiopental and ventilated with 70% nitrous oxide and 30% oxygen. A carotid arterial cannula and a Swan-Ganz catheter were inserted for hemodynamic monitoring. Pigs in groups 1 and 2 were then allowed to breathe spontaneously and groups 3 and 4 were mechanically ventilated. After obtaining a stable state, as judged by cardiovascular and respiratory parameters, the pigs were infused intravenously with cocaine hydrochloride (0.8 mg/kg/min) until the time of cardiac arrest. Respiratory and cardiovascular parameters, blood temperature, and sodium and potassium levels were monitored. The times of occurrence of respiratory arrests (RA), cardiac arrests (CA), and convulsions were recorded. Our results showed that RA is the primary cause of death in spontaneously breathing pigs and that mechanical ventilation significantly delayed the occurrence of CA (p < 0.05). Significant decreases in cardiac output, mean blood pressure, and heart rate as well as significant increases in systemic and pulmonary vascular resistances, central venous and pulmonary wedge pressures, and blood K+ levels were noted in mechanically ventilated pigs (p < 0.05). Variable hemodynamic responses were noticed in spontaneously breathing pigs. Our results also showed that no significant changes occurred in blood catecholamine levels when compared with baseline values associated with the infusion of toxic doses of cocaine.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1992

Continuous intravenous propofol with nitrous oxide for ocular surgery. A comparison with etomidate, alfentanil, nitrous oxide and isoflurane.

Propofol, administered intravenously for induction and as a continuous maintenance anaesthetic with nitrous oxide, was compared, in a group of elderly patients scheduled for ophthalmic surgery, with an anaesthetic technique (etomidate, alfentanil, nitrous oxide and isoflurane) specifically chosen to be haemodynamically stable and evanescent in action. Both techniques resulted in similar effects on blood pressure after induction, intubation and surgical incision, but propofol did not prevent increases in heart rate as effectively at these times. Furthermore, during maintenance anaesthesia, cardiovascular stability and anaesthetic depth were more easily achieved in the group where etomidate, alfentanil and isoflurane were used. Propofol decreased intra-ocular pressure after intubation, while in both groups recovery was rapid with no significant complications. A subgroup of patients receiving alpha-methyldopa had significantly longer post-anaesthetic recovery times.

Aged↗
PubMed1992

Blood usage in elective surgery--a 3-month audit at Groote Schuur Hospital, Cape Town.

Unnecessary crossmatching of blood is expensive and can result in unwarranted transfusion with needles exposure of patients to the risks of transfusion therapy. Since the extent of unnecessary crossmatching and transfusion at Groote Schuur Hospital, Cape Town had not previously been considered in detail, blood usage in elective surgery was studied over a period of 3 months in 1990 to determine adherence to the Maximum Surgical Blood Ordering Schedule (MSBOS), crossmatch transfusion ratios (CTRs) and transfusion appropriateness. Just over half of blood bank requests were equal to or less than the MSBOS. The overall CTR in elective surgery for this period was found to be 1,7, which, not unexpectedly, is higher than that for the whole of Groote Schuur Hospital (1,4). However, it ranged from 1,4 in cardiac surgery to 4,7 for neurosurgery. Twenty-nine per cent of postoperative transfusions were considered to have been excessive. Transfusion therapy in the peri-operative period is discussed and possible changes in strategy are suggested.

Blood Component Transfusion↗