Wound microbiology and associated approaches to wound management

The majority of dermal wounds are colonized with aerobic and anaerobic microorganisms that originate predominantly from mucosal surfaces such as those of the oral cavity and gut. The role and significance of microorganisms in wound healing has been debated for many years. While some experts consider the microbial density to be critical in predicting wound healing and infection, others consider the types of microorganisms to be of greater importance. However, these and other factors such as microbial synergy, the host immune response, and the quality of tissue must be considered collectively in assessing the probability of infection. Debate also exists regarding the value of wound sampling, the types of wounds that should be sampled, and the sampling technique required to generate the most meaningful data. In the laboratory, consideration must be given to the relevance of culturing polymicrobial specimens, the value in identifying one or more microorganisms, and the microorganisms that should be assayed for antibiotic susceptibility. Although appropriate systemic antibiotics are essential for the treatment of deteriorating, clinically infected wounds, debate exists regarding the relevance and use of antibiotics (systemic or topical) and antiseptics (topical) in the treatment of nonhealing wounds that have no clinical signs of infection. In providing a detailed analysis of wound microbiology, together with current opinion and controversies regarding wound assessment and treatment, this review has attempted to capture and address microbiological aspects that are critical to the successful management of microorganisms in wounds.     

The effects of measurement errors on relative risk regressions

This paper concerns the effects of random error in numerical measurements of risk factors (covariates) in relative risk regressions. When not dependent on outcome (nondifferential), such error usually attenuates relative risk estimates (shifts them toward one) and leads to spuriously narrow confidence intervals. The presence of measurement error also reduces precision of estimates and power of significance tests. However, significance levels obtained by using the approximate measurements are usually valid and as powerful as possible given the measurement error. The attenuation in risk estimate depends not only on the size (variance) of the measurement error, but also on its distributional form, on whether it is dependent on the true level of the risk factor (whether it is of "Berkson" type), on the variance and distributional form of true levels of the risk factor, on the functional form of the regression (exponential or linear), and on the confounding variables included in the model. Error in measuring confounding variables leads to loss of control of confounding, leaving residual bias. Uncomplicated techniques of correcting the effects of measurement error in simple models in which distributions are assumed normal are available in the statistical literature. For these corrections, information on measurement error variance is required. Some approaches appropriate for more general models have been proposed, but these appear to be insufficiently developed for routine application.     

Reading activities of registered nurses

This national study was designed to gather baseline data about the reading activities of registered nurses. Questionnaires were administered by nurse continuing educators to subjects (N = 1406) at 44 sites in 25 states and the District of Columbia. In a week, the mean amount of time devoted to professional literature was four hours, 48 minutes (SD = 3.88) plus eight hours, 12 minutes (SD = 5.15) to general material. This translated to reading one hour and 51 minutes per day, slightly more than the average adult. Educational level, position, and memberships were the best predictors of how much time was spent reading job-related material that might lead to self-development and enhancement of nursing practice.     

Do beta-amyloid (Abeta) deposits in patients with Alzheimer's disease and Down's syndrome grow according to the log-normal model?

The size frequency distributions of diffuse, primitive and classic beta-amyloid (Abeta) deposits were studied in single sections of cortical tissue from patients with Alzheimer's disease (AD) and Down's syndrome (DS) and compared with those predicted by the log-normal model. In a sample of brain regions, these size distributions were compared with those obtained by serial reconstruction through the tissue and the data used to adjust the size distributions obtained in single sections. The adjusted size distributions of the diffuse, primitive and classic deposits deviated significantly from a log-normal model in AD and DS, the greatest deviations from the model being observed in AD. More Abeta deposits were observed close to the mean and fewer in the larger size classes than predicted by the model. Hence, the growth of Abeta deposits in AD and DS does not strictly follow the log-normal model, deposits growing to within a more restricted size range than predicted. However, Abeta deposits grow to a larger size in DS compared with AD which may reflect differences in the mechanism of Abeta formation.     

Measurement tools used in the study of eccentric contraction-induced injury

The objective of this review is to evaluate the measurement tools currently used in the study of eccentric contraction-induced muscle injury, with emphasis on their usefulness for quantifying the magnitude and duration of the injury and as indicators of muscle functional deficits. In studies in humans, it was concluded that measurements of maximal voluntary contraction torque and range of motion provide the best methods for quantifying muscle injury. Similarly, in animal studies, the in vitro measurement of electrically elicited force under isometric conditions was considered to be the best of the measurement tools currently in use. For future studies, more effort should be put into measuring other contractile parameters (e.g. force/torque-velocity and force/torque-length relationships maximal shortening velocity and fatigue susceptibility) that may reflect injury-induced functional impairments. The use of histology, ratings of soreness and the measurement of blood or bath levels of myofibre proteins should be discouraged for purposes of quantifying muscle injury and/or functional impairment.     

The reliability of the "absent cistern sign" in assessing LP shunt function

OBJECTIVE: One of the difficulties with lumboperitoneal (LP) shunts has been non-invasively ascertaining shunt function. It has been previously reported that in the presence of a functioning LP shunt the perimesencephalic cisterns become obliterated--the "absent cistern sign". In order to more rigorously test this association we performed a retrospective analysis of LP shunt patients at the Hospital for Sick Children, Toronto. METHODS: The CT scans of all patients undergoing LP shunting over a 17 year period were reviewed. The "absent cistern sign" and ventricular size were compared against the results of either an isotope shunt study or surgical findings performed within 2 days of the CT. RESULTS: There were 38 CT scans (27 patients) performed within 2 days of an isotope shunt study and 15 CT scans (14 patients) performed within 2 days of a surgical intervention. These results give the absent cistern sign a sensitivity of 75% and a specificity of 57% when compared to the shunt isotope findings and a sensitivity of 100% and a specificity of 50% when compared to the surgical findings. Over 30% of the CT scans showed ventriculomegaly in the presence of a functioning shunt and, conversely, nearly 45% of the CT scans had normal or small lateral ventricles in the presence of a malfunctioning shunt. CONCLUSIONS: The "absent cistern sign" appears to reliably rule out a completely blocked shunt, but is less reliable in detecting a normal or partially obstructed shunt. Ventricular size correlates poorly with LP shunt function.     

Intracellular signals and cytoskeletal elements involved in oligodendrocyte progenitor migration

We have examined the potential roles of intracellular Ca2+ regulation and of multiple cytoskeletal elements in control of the directed migration of cultured oligodendrocyte progenitor cells (OPs). OPs were found to migrate in response to platelet-derived growth factor (PDGF) or to a lesser extent to basic fibroblast growth factor (FGF) in a non-additive manner. This response was inhibited by chelation of intracellular Ca2+ by using BAPTA-AM. OP migration was not evoked by the neurotransmitter agonists phenylephrine or methacholine, which elevate OP Ca2+ levels. Inhibition of the MAP kinase pathway with PD 098059 did not affect OP migration to PDGF. Within growth cone-like leading edges of migratory OP processes, monomeric and filamentous actin were found to be colocalized with myosin and filamentous actin was prominent in filopodia extending beyond the leading edge. Tubulin was distributed throughout OP processes and cell bodies. Inhibition of actin or tubulin polymerization, by using cytochalasin B or nocodazole, respectively, altered OP morphology and markedly impaired migration. Inhibition of the myosin ATPase by BDM, which prevents force-generating actin/myosin interactions, greatly inhibited the chemotaxic response at concentrations that did not disrupt cell morphology. These results indicate that growth factors stimulate OP migration by activating pathways which include intracellular Ca2+ regulation, and characterize the distribution of multiple cytoskeletal elements involved in the generation of directed OP movement.     

lschaemic heart disease: Non-invasive prediction of reperfusion and coronary artery patency by continuous ST segment monitoring in the GUSTO-I trial

In the GUSTO-I ECG ischaemia monitoring substudy, 1067 patientsunderwent continuous ST segment monitoring, using vector-derived12-lead (406 patients), 12-lead (373 patients) and 3-lead Holter(288 patients) ECG recording systems. Simultaneous angiogramsat 90 or 180 min following thrombolytic therapy were performedas a part of the prospective study in 302 patients. Infarct vessel patency was established as TIMI perfusion grades2 or 3 and occlusion as TIMI perfusion grades 0 or 1. Coronaryartery patency was predicted from ST trends up to the time ofangiography. Predictive values at 90 and 180 min after the startof thrombolysis were 70% and 82% for patency and 58% and 64%for occlusion, respectively. In retrospect, accuracy appearedgreatest (79–100%) in patients with extensive ST segmentelevation (400 µV), if both speed of ST recovery and extentof ST segment: elevation were taken into account. Although thethree recording systems differed considerably in signal processing,no significant difference in accuracy was demonstrated amongthese systems. We conclude that continuous ECG monitoring may help select highrisk patients without apparent reperfusion who may benefit fromadditional reperfusion therapy. As ST recovery may occur earlyafter the start of thrombolytics and accuracy of the test isrelated to peak ST levels, the use of on-line ECG monitoringdevices on emergency wards and cardiac care units is recommended.(Eur Heart J 1996; 17: 689–698)