Biomedical subjects
Publications and source records attributed to R A Simpson.
Delayed splenic rupture, though uncommon, is a recognised clinical condition and is associated with a significant mortality rate. In the vast majority of cases the patient re-presents with abdominal symptoms and/or signs of acute intraperitoneal haemorrhage. A case is presented of delayed splenic rupture presenting with jaundice attributable to intra-abdominal clot lysis.
BACKGROUND: The aim was to assess the role of plasma Big Endothelin (ET) 1 levels as a marker of disease presence and stage in colorectal adenocarcinoma. METHODS: Big ET-1 was measured in the plasma of 37 patients with colorectal cancer. Preoperative systemic plasma levels of Big ET-1 in patients with cancer were compared with levels in 20 age- and sex-matched controls. Portal plasma samples were collected at operation in addition to peripheral venous samples. Immunohistochemical staining for Big ET-1 was performed on a selection of primary tumour specimens and liver metastases. RESULTS: Median (range) preoperative systemic plasma levels of Big ET-1 were significantly higher in patients with cancer than in controls (1.0 (0.3-9.7) versus 0.2 (0.0-6.0) fmol/ml; P = 0.0001). Intraoperative portal plasma levels of Big ET-1 were significantly higher in patients with Dukes' 'D' disease than in patients with Dukes' A, B and C disease (2.1 (1.4-10.0) versus 1.2 (0.3-6.6) fmol/ml; P = 0. 01). Similarly, systemic plasma levels were significantly higher in patients with Dukes' 'D' disease than in those with localized disease (1.9 (1.2-9.7) versus 1.2 (0.2-8.3) fmol/ml; P = 0.01). The presence of microvascular invasion in the tumour specimens was associated with a significantly raised portal plasma level of Big ET-1 (1.6 (1.5-2.1) versus 1.1 (0.8-1.3) fmol/ml; P = 0.04). Immunohistochemistry localized Big ET-1 to the cancer epithelial cells. CONCLUSION: The plasma level of Big ET-1 is significantly raised in patients with colorectal cancer. Patients with liver metastases have significantly higher levels than those with localized disease.
OBJECTIVES: To establish the concentration of isopropanol that exerts the same immediate and sustained effects as n-propanol 60% v/v in surgical scrubbing, and to assess the performance of the test method proposed as the European standard in parallel experiments. DESIGN: Isopropanol at concentrations of 70%, 80%, and 90% v/v was tested in comparison with n-propanol 60%, the proposed reference preparation, in the draft method proposed by the European standard. A Latin square design was used with four balanced blocks of five volunteers each in four experimental runs that were spaced by intervals of 1 week each. Volunteers were allotted randomly to one of the four blocks. Independently, the volunteers' right and left hands also were randomized into two groups for the assessment of either immediate or sustained effects. SETTING: Two laboratories supervised by two investigators, one from Vienna, Austria, and one from London, The United Kingdom. METHOD: The release of skin flora from the fingertips of clean hands was assessed before and after treatment by immediate sampling from one hand and by sampling of the other, gloved hand after 3 hours. The mean log10 reductions (RF) of bacterial release achieved by rubbing the alcoholic preparations for 3 minutes onto the hands were established. RESULTS: For both experiments, the immediate effects of isopropanol 70% (RF, 2.0 and 2.1, respectively) were significantly smaller than those of the reference n-propanol 60% (RF, 2.4 and 2.6, respectively). This also was found with the sustained effects (RF, 0.7 and 1.1 vs 1.0 and 1.6, respectively). At 90%, isopropanol equalled the immediate effect of n-propanol 60%, whereas at 80% it proved slightly (although not significantly) less active. There were no significant differences in the results of both investigators. The sustained effects of isopropanol 80% and 90% were both larger than the reference in Vienna but were found smaller by the London investigator; none of the differences were significant. Mean RFs were significantly different between Vienna and London with n-propanol 60% and isopropanol 70%, but not with isopropanol at 80% or 90%. CONCLUSIONS: At 90%, isopropanol is as effective as n-propanol 60%, which was proposed by the European Committee for Standardization as a reference in testing products for surgical hand disinfection. It could, therefore, serve as an alternative if the proposed agent is undesirable for any reason. In parallel experiments by two investigators, the proposed test method proved well workable; the results were very similar and the conclusions identical.
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The efficacy of sodium hypochlorite was assessed against human immunodeficiency virus type 1 suspended in low (8% v/v) or high (80% v/v) concentrations of serum or in a high (80%) concentration of blood. In the presence of 8% serum, 100 p.p.m. available chlorine in the disinfectant test mixture inactivated 3.75 log TCID50 HIV/ml within 30 s. When the test mixture contained 80% serum, 500 p.p.m. available chlorine inactivated more than 4 log TCID50 HIV/ml in 1-2 min. Lower concentrations of available chlorine were unable to inactivate the virus completely. In the presence of 80% blood, 1000 p.p.m. available chlorine in the disinfectant test mixture was unable to inactivate 3.75 log TCID50 HIV/ml, although 2500 p.p.m. available chlorine was able to inactivate at least 1.5 log TCID50 HIV/ml. In all test mixtures, the chlorine rapidly became combined and thus less active. Our results emphasise the importance of cleaning prior to disinfection with sodium hypochlorite since it may prove to be ineffective in the presence of high levels of organic matter. In cases where prior cleaning is impossible, care must be taken to use the higher recommended concentration (a minimum of 10,000 p.p.m. available chlorine).
Procedures used for cleaning/disinfection of fibreoptic bronchoscopes and incidents of mycobacterial contamination were assessed by postal questionnaire. Information supplied by the Infection Control Doctor in 129 of 198 hospitals (65.2%) was used to audit local practice for compliance with national guidelines. Discrepancies between recommended and local practice included lack of specification of detergent/cleaning agent (57%), inadequate contact time for chemical disinfection (40%) and the use of tap water rather than sterile water for rinsing the disinfected bronchoscope (39.7%). Other procedural anomalies associated with mycobacterial contamination included failure to adhere to manufacturers' instructions to dismantle valves prior to cleaning and to autoclave valves/accessories. The association of mycobacterial incidents with the use of automatic washer/disinfectors (17 of 18 incidents) together with Department of Health warnings of build-up of biofilm within these chemical-process machines gives further cause for concern.
Alcohols are commonly used as disinfectants for skin, surfaces and immersion of some medical instruments. Measurements of the activity of alcohols against human immunodeficiency virus type 1 (HIV-1) must take account of the compatibility of neutralizers used to stop the disinfectant reaction, and of toxicity to the cell line used to detect residual virus. We have developed protocols to measure the efficacy of alcohols against HIV in suspension and dried onto surfaces in the presence of high and low protein concentrations. High titres of HIV in suspension were rapidly inactivated by 70% ethanol, independent of the protein load. When virus was dried onto a glass surface, the rate of inactivation decreased when high levels of protein were present. Due to its rapid evaporation, a spray or a wipe with alcohol cannot be guaranteed to disinfect a surface contaminated with blood or other body fluids without preliminary cleaning.
A common assertion in the literature is that Langhans cells in placental villi decline in number during gestation but this is a misinterpretation which may be caused by the greater growth of villous surface area compared with trophoblast volume. To test this possibility, human placentae were collected at 12-41 weeks of gestation for a cross-sectional study on the packing density of nuclei within villous trophoblast. Numbers of nuclei in the cyto- and syncytiotrophoblast were estimated using a design-based stereological device, the physical disector (parallel pairs of sections). Surface areas were estimated in order to assess the overall growth of villous arborizations. Packing densities of nuclei were calculated and expressed as numbers/1000 microns 2 of villous surface. Densities decreased during gestation and this can be explained by expansion of villous surface area and thinning of trophoblast. The biggest drop in packing density of cytotrophoblast nuclei (30 per cent) occurred between 17-21 and 22-26 weeks and this period coincided with the largest changes in villous surface area (62 per cent increase) and trophoblast thickness (30 per cent decrease). Results are consistent with the notion of an epithelial proliferative unit of constant volume and comprising about nine syncytiotrophoblast nuclei per Langhans cell.
Cell-free and cell-associated human immunodeficiency virus cultures suspended in 10% serum remained infectious for several weeks at room temperature. The stability was further increased when cell-associated virus was suspended in neat serum. When dried onto a glass coverslip, virus remained infectious for several days, although cell-associated virus lost infectivity more rapidly than cell-free virus.
A cross-sectional sample of human placentae was collected at 12-41 wk, and growth mechanisms within villous subcompartments (trophoblast epithelium, stroma and fetal capillary endothelium) were assessed using state-of-the-art design-based stereological methods. Physical disectors (adjacent pairs of sections) were used to count nuclei in syncytiotrophoblast and in cells of the cytotrophoblast, stroma and endothelium. The volumes of trophoblast and stroma and the surface areas and lengths of capillaries were employed to assess the overall growth of each compartment. Growth within compartments was monitored as total number of nuclei (a measure of nuclear proliferation) and compartment size per nucleus (a measure of hypertrophy). During gestation, all compartments grew dramatically. Numbers of nuclei increased exponentially and followed an uninhibited growth model. Volumetric growth of the placenta did not keep pace with the increase in total nuclear number (all types). Growth of trophoblast was exclusively hyperplastic and proceeded at an average net recruitment rate of 15 million nuclei per hour with a numerical predominance of syncytiotrophoblast nuclei of 9:1. There was no evidence of hypertrophy: trophoblast volume per nucleus averaged 1080 microns 3. Growth within stroma involved cell proliferation (17 million nuclei per hour) and the volume of stroma per nucleus declined at a rate of about 24 microns 3 per week. Capillary growth was hyperplastic (5 million endothelial squames per hour) and, possibly, hypertrophic (the mean area of a squame increased by about 18 microns 2 per week). Linear growth of vessels exceeded cellular recruitment and the density of squames along the capillaries decreased each week by about 5 per mm.(ABSTRACT TRUNCATED AT 250 WORDS)
For the hospital microbiologist, the use of guidelines, policies and standards are an integral part of their professional duties. Both patient-related and laboratory activities involve awareness of specific procedures and the use of equipment or products which have been accepted as appropriate for a particular purpose. The means by which policy is formulated, the guidance available and the standards specified, differ widely from country to country. In the UK, there are few legal requirements or statutory regulations in this area. In consequence, there may be some differences in both the nature and the method of implementation of policies from hospital to hospital. There is increasing concern that legislation and standards produced not only by the UK but also by Europe may impose regulations on infection control and laboratory practice and in particular that such mandatory controls may have adverse effects. These are variously perceived as specifying inappropriate standards, inhibiting clinical freedom and stifling innovation. Such concern is embodied in the question 'are we in control?'.
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Men with indwelling catheters and men and women with suprapubic catheters were studied in their homes. Urine and blood were cultured and body temperature recorded after every catheter change. Nearly all patients had infected urine after 4 weeks of catheterisation, and all had bacteriuria after longer periods, usually with a mixture of organisms. Culture on selective media revealed a wider range of organisms than was detected on routine C.L.E.D. and blood agar with antibiotic sensitivity disks, but routine culture gave adequate information for clinical purposes. Bacteraemia was demonstrated after 20 of 197 changes of urethral catheter and after one of 19 changes of suprapubic catheter; but no patient had pyrexia or other symptoms. However, two had rigors on other occasions. When assessing "risk factors" for blood-stream infection in catheterised patients, it is important to record the total incidence of bacteraemia, asymptomatic as well as symptomatic.
In-patients with venous leg ulcers showed increased healing rates with a hydrocolloid dressing (Granuflex), as compared with a traditional paraffin gauze dressing (Jelonet), in a randomized sequential crossover trial, although the difference was not statistically significant. Bacteriological studies showed that the hydrocolloid dressing favoured growth of both aerobes and anaerobes in significantly greater numbers compared with paraffin gauze. Heavy bacterial colonization had no effect on the healing rates of the ulcers. Granuflex is said to produce an anaerobic environment--survival of Pseudomonas aeruginosa, a strict aerobe, under Granuflex dressings, makes this seem unlikely.