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Biomedical subjects

P Armstrong

Publications and source records attributed to P Armstrong.

At least 73 records · Page 4Linked to original sources
PubMed1994

Non-invasive assessment of diffuse liver disease by in vivo measurement of proton nuclear magnetic resonance relaxation times at 0.08 T.

44 patients with a range of parenchymal liver diseases diagnosed by biopsy or laboratory investigations underwent proton nuclear magnetic resonance (NMR) relaxometry of the liver at 0.08 T. T1 maps were produced using an interleaved saturation recovery and inversion recovery sequence and T2 maps using a four echo Carr-Purcell-Meiboom-Gill sequence. Significantly raised relaxation times compared with a previously studied group of 42 normal volunteers were found in groups of patients with alcoholic cirrhosis (p < 0.001 for T1 and T2), chronic active hepatitis (CAH) (p < 0.01 for T1 and T2) and minor liver abnormalities (p < 0.01, T2 only). T1 was significantly higher in cirrhotics than in patients with CAH (p < 0.002) and minor abnormalities (p < 0.001). This suggests a role for relaxometry in the confirmation of the presence of cirrhosis (sensitivity = 75%, specificity approximately 97%, taking T1 > 266 ms as a positivity criterion). Reduced T2 values were found in patients with liver iron overload prior to venesection (p < 0.001 versus normals, p < 0.02 versus venesected patients). Although this latter test has relatively low sensitivity and specificity, it may have a role in the monitoring of treatment for iron overload.

Adult↗
PubMed1994

The significance of perioperative cultures in open pediatric lower-extremity fractures.

The value of perioperative cultures in 86 open pediatric lower-extremity fractures was assessed. Thirteen infections were identified, for an incidence of 15%. The predebridement culture was positive in 63% of wounds, and the postdebridement culture was positive in 40%. In the 13 wounds with infection, the infecting pathogen was found among the organisms grown on positive predebridement cultures 29% of the time, and on 60% of post-debridement cultures. Neither culture was of value in predicting the identity of a potential subsequent infecting pathogen. There was no significant difference in the rate of infection for negative cultures versus positive cultures; however, a negative predebridement culture was associated with a 94% chance of avoiding infection, and a negative postdebridement culture correlated with a 79% probability that infection would not occur. A positive culture result was less useful, however, because the infection rate remained low in these instances. Predebridement cultures were highly sensitive (88%) in identifying wounds that developed infection; however, the false positive rate was high, resulting in a specificity of only 43%. Postdebridement cultures, although somewhat more specific (63%), lacked sensitivity (50%). Clearly the routine use of perioperative cultures in open pediatric lower-extremity fractures must be questioned. Further prospective study is needed to confirm the validity and general applicability of the results of this retrospective review.

Bacteria↗
PubMed1993

An ethologist aboard HMS Beagle: the young Darwin's observations on animal behavior.

Darwin's notes from the Beagle period abound with observations on animal behavior. Although in places anecdotal and anthropomorphic, they include many detailed, lively comments of the activities of birds, reptiles, mammals, crustacea, insects, and other invertebrates. In his comparative approach, belief in the importance of heredity, an understanding that behavior might be of assistance in taxonomy, and that it was linked with both the organism's morphology and habitat, and his attempts at experiments, Charles Darwin in his early and mid-twenties was using techniques and concepts that were to be of great significance in his later work.

Anatomy, Comparative↗
PubMed1993

Fibroblast behavior in the embryonic chick heart.

Intracardiac fibroblasts (mesenchymal cells) of Hamburger and Hamilton stage 36 chick heart reside in the epicardium and atrioventricular valves. The characteristics of the epicardial fibroblasts include segregation from the myocytes of the heart wall myocardium, voluminous extracellular matrix production, and some cell proliferation activity. The atrioventricular fibroblasts intermingle with myocytes at the mutual border between these tissues, produce smaller amounts of extracellular matrix, and show very active cell proliferation. Is the behavior of each population of fibroblasts predetermined or is each responding in a reversible fashion to local environment? A cell aggregate culture system, which permits 3-dimensional cell-cell and cell-matrix interactions, is used to study the behavior of each isolated population of fibroblasts in vitro. In the presence of serum-free medium, each population produces very little extracellular matrix, has relatively low mitotic activity, and does not segregate from myocytes when the aggregate is composed of randomly intermixed myocytes and fibroblasts. In the presence of chicken serum, each population increases matrix production, increases cell proliferation, and sorts from myocytes. Thus, we suggest that the two populations of fibroblasts in the developing heart are responding to local environments and the differences observed in vivo are not the consequence of irreversible states of cellular differentiation.

Animals↗
PubMed1993

The radiological investigation of occult ectopic ACTH-dependent Cushing's syndrome.

The radiological features of 14 patients with Cushing's syndrome due to 'occult' ectopic ACTH syndrome have been reviewed. In 11 of the 14 patients (79%), the ACTH-producing tumour was located in the thorax. Bronchial carcinoid tumours (eight patients) were the single most common source of 'occult' ectopic ACTH production with thymic carcinoid tumours (two patients) and mediastinal metastases from a medullary carcinoma of the thyroid gland (one patient) accounting for the other intrathoracic tumours. The tumours were usually small with five of the eight bronchial carcinoid tumours measuring between 4 and 10 mm in diameter. Since it remains difficult to distinguish between pituitary-dependent Cushing's disease and 'occult' ectopic ACTH-dependent Cushing's syndrome both clinically and biochemically, the role of radiology remains vital.

ACTH Syndrome, Ectopic↗
PubMed1992

Magnetic resonance imaging of anal fistulae.

Success of surgery for an anal fistula depends on accurate assessment of the fistula; however, such assessment is technically difficult. We have done a prospective study that determined the accuracy of magnetic resonance imaging (MRI) in demonstrating the course of fistulae, by comparing MRI scan interpretations with subsequent operative findings. 16 patients (mean [range] age 42 [24-66] years) had MRI followed by surgery within a mean of 22 (1-101) days. MRI scan interpretations agreed precisely with independently documented operative findings in 14 of 16 patients. MRI is an accurate method of delineating anal fistulae, and should be considered for patients with difficult fistulae that recur despite skilled attention because it demonstrates abnormalities that might otherwise be missed.

Adult↗
PubMed1992

Confronting the issues of patient safety and investigator conflict of interest in an international clinical trial of myocardial reperfusion. Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO) Steering Committee.

The Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO) trial is a large scale international trial of new myocardial reperfusion strategies. The primary hypothesis is that early and sustained coronary artery recanalization will be associated with a significant reduction in mortality. The four regimens that are being tested are 1) streptokinase with subcutaneous heparin; 2) streptokinase with intravenous heparin; 3) accelerated recombinant tissue-type plasminogen activator (rt-PA) with intravenous heparin; and 4) combination streptokinase, rt-PA and intravenous heparin. The planned recruitment of 41,600 patients in 1,500 sites from 15 countries is expected to be completed by December 1992 and will enable detection of a 15% reduction or 1% absolute difference in mortality compared with that associated with standard therapy (streptokinase and subcutaneous heparin). In designing the trial, two important issues were directly addressed. First, a strategy was developed to provide assurance of patient safety during large scale investigational use of an aggressive thrombolytic regimen. This includes fascimile transmission of a one-page safety summary form to the Data Coordinating Center within 24 h of death or discharge, acceptance of the concept of "net clinical benefit" and close surveillance of the trial's progress by the independent Data and Safety Monitoring Committee. Second, to avoid potential conflict of interest beyond elimination of any position of financial equity, the Steering Committee unanimously voted to prohibit any honoraria for speaking engagements, payment for consultancy or travel or reimbursement of any kind from any of the five corporate sponsors until 1 year after publication of the results. Incorporation of these approaches may facilitate the design of future large scale randomized trials in cardiovascular medicine.

Biomedical Research↗
PubMed1992

Proton NMR relaxation times in the normal human liver at 0.08 T.

The spin-lattice (T1) and spin-spin (T2) relaxation times of liver in 42 normal volunteers (21 male and 21 female) were measured using a calibrated 0.08 T resistive imager capable of accurate and reproducible relaxometry. T1 was determined using an interleaved gradient echo saturation recovery and inversion recovery technique and T2 using a four-echo Carr-Purcell-Meiboom-Gill sequence. The ranges obtained were T1 = 213 +/- 14 ms and T2 = 66 +/- 5 ms. More specific ranges were obtained for each sex and for younger and older subjects. A small variation in T1 was found between older (greater than 40 years) and younger (less than 40 years) subjects, but no such effect was observed in the case of T2. No significant variations were found when female volunteers were imaged at weekly intervals through the menstrual cycle, when a male volunteer was imaged repeatedly over the course of several months or when male volunteers consumed small quantities of alcohol.

Adult↗
PubMed1992

Case report: primary lymphoma of bone--MRI appearances with pathological correlation.

A case of primary lymphoma of bone involving the proximal tibia is presented. The magnetic resonance (MR) appearances were unusual for a primary malignant tumour, with predominantly low signal intensity on both T1- and T2-weighted images. This correlated with marked fibrosis on histology. These observations are discussed in the context of previous reports of MRI in bone lymphoma.

Adult↗
PubMed1992

Surgical face masks are effective in reducing bacterial contamination caused by dispersal from the upper airway.

We have studied the effectiveness of surgical face masks in reducing bacterial contamination of a surface, produced by dispersal of organisms from the upper airway. Twenty-five volunteers were asked to speak at blood agar plates positioned in close proximity to the mouth, initially whilst not wearing a face mask and then wearing a surgical face mask over the mouth and nose. A fresh face mask almost completely abolished bacterial contamination of agar plates 30 cm from the mouth. After 15 min there was an increase in the level of contamination which was statistically insignificant.

Adult↗
PubMed1992

Perceptions of psychological problems in general practice: a comparison of general practitioners and psychiatrists.

All general practitioners and psychiatrists working in a single health district were sent a questionnaire on their perceptions of the prevalence of psychological problems among patients consulting in general practice. One hundred and twenty-one GPs (75%) and 10 (83%) psychiatrists responded. GPs and psychiatrists agreed that up to 20% of consulting patients were likely to be clinically depressed; they also agreed on the most appropriate management, although GPs tended to be more conservative than psychiatrists would advise on making use of hospital services. GPs, however, believed non-specific psychological problems to be significantly less common than did psychiatrists. This expectation may help explain the reported failure of GPs to diagnose all psychological problems identified by formal psychiatric instruments.

Adult↗
PubMed1992

Thoracic epidural anaesthesia and primary pulmonary hypertension.

Patients with primary pulmonary hypertension occasionally present for surgery. Anaesthesia requires continuous cardiovascular monitoring and maintenance of stable pulmonary and systemic haemodynamics. The management of a patient with severe pulmonary hypertension, undergoing open lung biopsy under a combination of general anaesthesia and thoracic epidural analgesia is reported and the problems of primary pulmonary hypertension are discussed.

Adult↗
PubMed1992

Development of clinical guidelines in a health district: an attempt to find consensus.

OBJECTIVE: To formulate consensus based guidelines for antenatal care in a health district. DESIGN: Prospective formulation of draft guidelines by a working group of consultant obstetricians and general practitioners with an obstetric interest, canvassing opinions of all GPs in the district by questionnaire, and revision and final circulation of the guidelines. SETTING: One health district. SUBJECTS: All 160 GPs in the district and members of the working party. MAIN MEASURES: Questionnaire responses to specific proposals within the draft guidelines for managing anaemia, antepartum haemorrhage, and hypertension. RESULTS: 136 GPs responded (response rate 85%); responders and nonresponders did not differ in age, sex, or presence on obstetric list. Overall they favoured more conservative management than suggested in the guidelines. For example, only 38% (44/116) prescribed iron routinely and 34% (38/113) referred to hospital for haemoglobin concentration of < or = 10 g/l; 10% referred women unnecessarily for oedema unassociated with proteinuria; and 20% managed active bleeding progressing to old brown staining as an urgent admission. The guidelines were revised according to the relative weight of the views obtained. CONCLUSION: Establishing guidelines is mainly a political process. Canvassed views influenced guidelines most when internal disagreement existed within the working party. IMPLICATIONS AND ACTION: Regular revising of the guidelines is planned, which, in conjunction with repeating the questionnaire to monitor changing practice, will allow a long term district wide clinical review.

Attitude of Health Personnel↗