Changes in transthoracic electrical impedance during endotoxemia in dogs

Our aim was to investigate the role of hematocrit (H) and respiration in transthoracic electrical impedance during endotoxemia. Transthoracic electrical impedance at end-expiratory apnea (Z0) and at end-inspiration (Zmax), H values, and extravascular lung water level (EVLW), estimated by means of gravimetric analysis and the impedance method, were measured in splenectomized and mechanically ventilated dogs. In endotoxemia, there were increases in Z0, Zmax, H and the respiratory frequency. In the splenectomized dogs, both impedances slightly increased without any significant change in H. In the ventilated dogs, Z0, and Zmax increased similarly, while H increased. In the splenectomized, ventilated dogs, no changes were found in the impedances or H. The EVLW values showed that there was no serious edema in the endotoxemic groups. The results suggest that Z0 increased mainly in association with the increase in H. We conclude that the noninvasive measurements of the changes in impedance can be used for continuous monitoring of the fluid and gas shifts in the thorax.

Strategies used by burns nurses to cope with the infliction of pain on patients

The infliction of pain on patients is part of the daily routine for many nurses, particularly those who work in burns units, but there has been little help available for nurses to develop useful ways of coping with such circumstances. Few researchers have considered how the ways that nurses manage their feelings about pain may provide insights into the reasons why available pain control methods have not been fully practiced. The aim of this study was to identify the range of coping strategies used by nurses when conducting painful procedures. Nurses working in five burns units were interviewed about their feelings when it was necessary for them to inflict pain on patients in the course of giving patient care. Content analysis was used to identify the kinds of coping strategies used by nurses to manage their feelings about such situations. Fourteen kinds of strategy were identified and were then grouped into four categories: (i) distancing oneself from the patient's pain; (ii) engaging with the patient's pain; (iii) seeking social support and (iv) reconstructing the nurse's core role. The use of each of these categories of coping have implications for both the management of patient's pain and the nurse's emotional well-being. While distancing oneself from the patient's pain was the most prevalent way for nurses to cope with their feelings about causing pain to patients, all types of coping strategies had their advantages. It is possible that combinations of various strategies may be the most effective way for nurses to deal with their patients' pain.

Outcomes, problems and quality of life with the implantable cardioverter defibrillator

The survey aimed to assess the outcomes, problems and quality of life (QOL) in recipients of the implantable cardioverter defibrillator (ICD). Average QOL was 6.4 (1-10 scale), but lower in those who had received shocks (p < 0.05); 54% of patients had been shocked at least once. Usual daily activities were resumed by 72%, and driving by 76% of patients; 96% would recommend the ICD to others. Primary information sources were the implanting cardiologist and manufacturer's booklet. This study concluded that most ICD recipients have good QOL, but it is reduced in those who have been shocked by the defibrillator. Most eventually know enough about living with the ICD, but desire more education and support at the time of ICD insertion. Nurses could meet this need.

ATP and integrity of human red blood cells

In spite of the well known significance of ATP in the energy dependent life processes, the role of ATP in maintaining cellular integrity is poorly understood. A possible model for studying ATP dependent life processes is to monitor the kinetics of changes seen intra/extracellularly during ATP depletion. In our model system anticoagulated human whole blood was incubated at different temperatures to reduce intracellular ATP without addition of any chemicals. The red blood cells in their own plasma were incubated for several days at 4 degrees C or at 37 degrees C, and ATP, glucose, K+, Na+, hemoglobin, water content, mean corpuscular volume (MCV), pH and Ca2+ were analyzed in time-sequences. All the examined parameters remained practically unchanged at 4 degrees C, while at 37 degrees C total ATP and glucose decreased parallel and after a transient increase of MCV, the water content of red blood cells decreased. As the actual ATP fell below 10% of the initial ATP content (at 48 h), the release of potassium sharply increased. Release of hemoglobin started only after 96 hours of incubation. Maximums of changes of the examined parameters were found at different time intervals. The maximal speed of concentration changes for glucose was found at 12-24 hours of incubation and at 24-36 hours for ATP, at 48-60 hours for K+(-)Na+ and after 96 hours for hemoglobin.

Mast cell degranulation prior to ischemia decreases ischemia-reperfusion injury in the canine small intestine

OBJECTIVE

To determine the impact of previous mast cell degranulation on intestinal ischemia-reperfusion-induced mucosal damaged.

MATERIALS

The hemodynamic and morphological consequences of complete arterial occlusion were evaluated in anesthetized dogs. The mast cell degranulator Cremophor-E1 (n = 5) and Compound 48/80 (n = 5) were used to investigate the involvement of gastrointestinal mast cells in ischemia-reperfusion-induced tissue reactions. Seven dogs subjected to complete segmental arterial occlusion served as controls. Intestinal biopsies taken at the end of 120-min ischemia and after 120 min of reperfusion were evaluated histologically.

METHODS

The number of mast cells was determined and the degree of mucosal damage was evaluated according to the 5 grade Chiu scale. Mucosal histidine decarboxylase activity was measured in tissue samples and the rate of release of histamine was determined from the venous effluent of the ileal segment.

RESULTS

In the control group, 120-min reperfusion significantly increased the plasma histamine level, and induced a severe tissue injury. In the compound 48/80 and Cremophor-E1-pretreated groups, the reduction in the baseline number of mast cells in the villi was 37% and 53%, respectively, and the ischemia-reperfusion-induced release of histamine was significantly decreased. In these groups, the basal mucosal histidine decarboxylase activity was significantly increased and the degree of damage of the intestinal mucosa was significantly reduced.

CONCLUSION

It is proposed that mast cell degranulation prior to ischemia may induce a potentially protective mechanism in the small bowel mucosa and decreases ischemia-reperfusion injury in the dog.

It's all in a name. When is a 'Delphi study' not a Delphi study?

As nursing researchers we need to fully understand the origins of the methods we are using in research investigations. Without an in-depth understanding, we may find ourselves violating fundamental underpinning assumptions or conventions through ignorance, and the resulting studies are unlikely to stand up to tests of congruence and rigour. This paper is a discussion of some complexities encountered while exploring the literature on the Delphi technique, a research method we had believed to be straightforward. The Delphi method had been used extensively since its development in the 1950s, and its use in nursing research appears to be increasing. Our explorations revealed that, rather than a simple means of obtaining the judgments of experts, modifications and adaptations over the years have dramatically changed 'the' Delphi. Anyone wishing to use the method needs a sound knowledge of complex theoretical issues associated with its implementation.

The role of mast cell degranulation in ischaemia-reperfusion-induced mucosal injury in the small intestine

The role of the intestinal mast cell system in the pathophysiology of postischaemic mucosal lesions is not understood. The present goals were to investigate the contributions of mast cells and mast cell-derived vasoactive mediators to mucosal injury caused by arterial occlusion. We evaluated the intestinal ischaemia-reperfusion-induced local morphological changes in mast cell-depleted anesthetized dogs. Animals subjected to complete segmental intestinal ischaemia and reperfusion served as controls. The selective mucosal-type mast cell degranulator Cremophor-El and the nonselective mast cell depleter Compound 48/80 were used to investigate the involvement of mast cells in reperfusion-induced tissue reactions. Ileal biopsies taken at the end of 120 min of ischaemia and after 120 min of reperfusion were evaluated histologically. The number of mast cells was determined and the degree of mucosal damage was evaluated according to the 0 to 5-grade Chiu scale. Mucosal histidine decarboxylase activity was measured in tissue biopsies and the rate of release of histamine was determined from the venous effluent of the segment. In the control group, 120 min reperfusion induced a severe tissue injury. In the Compound 48/80 and Cremophor-El-pretreated groups, the reduction in the baseline number of mast cells was 37% and 53%, respectively, and the basal mucosal histidine decarboxylase activity was significantly increased. In these groups, the ischaemia-reperfusion-induced release of histamine was significantly decreased, and the degree of damage of the intestinal mucosa was significantly reduced. Mucosal mast cell degranulation plays an important role in the initiation of tissue injury after intestinal ischaemia-reperfusion. Depletion of mast cells prior to ischaemia decreases the severity of mucosal damage, probably in consequence of the stimulation of mucosal histidine decarboxylase activity.

[Beneficial effect of the ACE inhibitor captopril in normotensive patients with insulin-dependent diabetes]

The increase of glomerular filtration can often be observed in patients with insulin dependent diabetes mellitus, even in the early stage of the disease and it does not require the presence of microalbuminuria. This phenomenon can be explained by vasoconstriction occurring in the efferent arterioles. Eighteen normotensive, diabetic patients (aged: 28-42) who developed increased glomerular filtration were recruited in this study. The specific objectives were: 1. to study the beneficial effect of angiotensin converting enzyme inhibitor on the glomerular filtration, 2. to evaluate the effect of this treatment on blood pressure and hemodynamic parameters in normotensive, diabetic subjects. After a placebo period of one week, patients were treated orally a daily dose of 3 x 6.25 mg of captopril for twelve weeks. Glomerular filtration was assessed by the isotopic clearance method and blood pressure recordings were taken every 30 minutes throughout a day using an automatic programmable device. Preload, afterload and linear ejection fraction were estimated by echocardiograph, whereas cardiac index was measured by isotopic first pass technique. At the end of the treatment period a significant decrease of glomerular filtration was observed (from 141.9 +/- 10 ml/min to 98.9 +/- 12 ml/min; p < 0.01. Similarly, the afterload exhibited a significant drop due to drug treatment (45.6 +/- 5.8 x 10(3) dyn/cm2 vs. 55.4 +/- 4.7 x 10(3) dyn/cm2 at the end of the placebo period (p < 0.01). However, preload, linear ejection fraction, and cardiac index did not significantly change during the treatment. According to the results obtained from this study a beneficial effect of captopril on the early development of the glomerular hyperfiltration was demonstrated in normotensive diabetic patients who did not develop microalbuminuria. This issue needs to be investigated further in a large scale clinical trial.

The role of endothelin-1 in circulatory changes during hypodynamic sepsis in the rat

Our objective was to investigate the significance of endogenous endothelin-1-induced systemic circulatory reactions during hypodynamic sepsis. In the first part of this study, we observed the changes in global hemodynamic parameters in Wistar rats after exogenous endothelin-1 administration in order to test an intervention strategy aimed at preventing the development of hypodynamic cardiovascular derangement during intraabdominal sepsis. Cardiac output, mean arterial blood pressure, and peripheral vascular resistance were recorded, and the endothelin-A receptor antagonist BQ-610 and the endothelin-B receptor antagonist IRL-1038 were used to investigate the role of receptor subtypes in circulatory changes. In addition, the effects of treatment with the novel endothelin-A receptor inhibitor ETR-P1/fl peptide were examined in endothelin-1-treated anesthetized rats. The injection of 1 nmol/kg endothelin-1 induced a significant rise in peripheral vascular resistance, a transient increase in mean arterial pressure, and a decrease in cardiac output. Administration of the endothelin-A receptor antagonist BQ-610 and ETR-P1/fl peptide increased cardiac output and decreased systemic vascular resistance in the controls and in animals treated with exogenous endothelin. In the second part of the study, the animals were instrumented for hemodynamic monitoring and randomized to undergo cecal ligation and perforation for 8 h or control laparotomy. Septic animals with cecal ligation and puncture were normotensive and hypodynamic, with a significantly increased total peripheral resistance throughout the 8 h observation period. ETR-P1/fl peptide treatment started after the induction of sepsis significantly increased cardiac output and decreased systemic vascular resistance almost to control levels. We conclude that endogenous endothelin-1 contributes significantly to the systemic hemodynamic alterations during hypodynamic circulatory response, and the inhibition of endothelin-A receptors may improve global hemodynamic status in this phase of sepsis.

Serial sectioning of sentinel nodes in patients with breast cancer: a pilot study

BACKGROUND

Recent reports indicate that the sentinel node, defined as the first regional lymph node to receive lymphatic fluid from the breast, accurately represents the metastatic status of the primary breast cancer. However, routine single section examination of the regional nodes, including the sentinel node, underestimates the true incidence of metastases. The goal of this study is to determine whether multiple sectioning of sentinel nodes will detect occult metastases in operable breast cancer.

METHODS

Nineteen patients with invasive breast cancers were injected with technetium-99m sulfur colloid solution around the tumor or at the biopsy site before lumpectomy and axillary lymph node dissection (ALND) or mastectomy. The labeled sentinel lymph nodes (SLND) were bivalved, and a central section was taken for hematoxylin and eosin (H & E) examination. The sentinel nodes of 13 patients, which were reported to be negative for metastases, were serially sectioned at 0.5-mm intervals and stained with H & E and a cytokeratin stain, CAM 5.2.

RESULTS

In the 13 node-negative patients, occult metastases were found in the sentinel nodes of 3 patients (23%). Two were seen on H & E and one by cytokeratin stain. The mean numbers of SLND and ALND in this series were 2.6 and 12.5, respectively, and the average number of sections for the two groups was 14 and 1, respectively.

CONCLUSION

Multiple sectioning of the sentinel node or nodes detects occult metastases and changes the staging of breast cancer.

Australian nurses and device use: the ideal and the real in clinical practice

Clinical nurses use an increasing number of technological devices when providing care. While the clinical devices themselves must undergo rigorous multidimensional assessment, it is the proficiency of the user that ultimately determines the devices' efficacy. Thus, the knowledge, skills and attitudes that nurses bring to their decision-making and use of technology are crucial elements in the technology assessment process. Technological proficiency is imperative in the current climate of rapid patient throughput in complex technological environments. This paper reports some of the findings of an Australian study, using two national Delphi panels, whose primary objective was to determine the knowledge, skills and attitudes required of expert clinicians for practice in cardiac care. Panels of 28 educators and 42 cardiac nurse clinicians completed a questionnaire indicating the importance of 107 characteristics of expert cardiac practice for both the 'real' and 'ideal' worlds of practice. Comparative results will be reported for 29 items within the thematic groups. Effective use of technology, Informed decisions regarding equipment and Critical approach to the use of technology. Both panels accepted all 29 items in these three thematic groups but indicated differences in the level of agreement on the importance of items between the 'real' and 'ideal' worlds of practice. Discussion centres around those areas where improvement is needed.

A comparison of the effects of patients' pain on nurses working in burns and neonatal intensive care units

Nurses are more likely than other health professionals to be exposed to individuals who suffer severe pain for extended periods of time. Such exposure is likely to arouse emotional distress which not only has implications for their occupational health but may interfere with their ability to manage pain effectively. This study compared the emotional reactions to their patients' pain, of nurses who were exposed to patients with severe and obvious pain (nurses working in burns units) and nurses whose patients' pain is uncertain because they are unable to communicate (nurses working in neonatal intensive care units). The results showed that pain generated greater anxiety in nurses caring for patients with severe burns, but that they also demonstrated a greater sense of personal competence and control over the management of their patients' pain. The findings also showed that when dealing with patients' pain the morale of nurses was linked to: (a) perceived challenges to their images of themselves as alleviators of pain; (b) the extent to which their sense of personal vulnerability was aroused by contact with patients experiencing severe pain; (c) their beliefs about their ability to assess patients' pain; and (d) the quality of their professional relationships with the medical staff who controlled the most powerful forms of pain relief.

Endothelin-1-induced circulatory response in the rat: the role of ETA and ETB receptors

Production of the powerful vasoconstrictor endothelin-1 (ET1) is increased in a number of pathological conditions. This study was performed 1. to assess the effects of a twofold elevation of circulating ET1 on global hemodynamics and cardiac function, and 2. to determine the ET receptor subtypes that are responsible for this action. We have used the ETA receptor-selective antagonist BQ 610, the novel ETA receptor antagonist ETR-Pl/fl peptide and the specific ETB receptor antagonist IRL 1038 to investigate the role of these receptor subtypes in mediating circulatory changes induced by ET1 in anesthetized Wistar rats. ET1 infusion produced a significant rise in mean arterial pressure (MAP), elevated total peripheral resistance (TPR), and decreased cardiac output (CO). BQ 610 and ETR-Pl/fl pretreatment significantly attenuated the ET1-induced hemodynamic changes. Pretreatment with IRL 1038 had no effect on CO, but significantly reduced MAP and TPR elevation 20 min after ET1 infusion. These results suggest that ET1 may contribute to circulatory failure in conditions with increased ET1 production via a mechanism involving ETA receptors. ETB receptors, albeit to a lesser extent than ETA receptors, are also involved in mediating ET1-induced peripheral vasoconstriction in the rat.

Effects of antiendothelin treatment on the early hemodynamic changes in hyperdynamic endotoxemia

We have performed a series of experiments to study the effects of a newly developed antisense homology box-derived endothelin (ET) antagonist peptide (ETR-P1/fl) on the early hemodynamic changes in a hyperdynamic endotoxemic dog model. Mean arterial pressure (MAP), cardiac output (CO) and myocardial contractility (MC) were measured in closed-chest animals. Plasma levels of ET-1,2 were determined by radioimmunassay. A hyperdynamic circulatory response was elicited with a 2-hour infusion of 5.3 micrograms/kg of E. coli endotoxin (ETX). Control and ETX-treated animals received an infusion of ETR-P1/fl (0.1 mg/kg) i.v. ETX treatment decreased MAP and MC, increased initially CO, and a long lasting elevation in the plasma ET level was observed. In ETX-treated animals the administration of ETR-P1/fl significantly prolonged the increase in CO and inhibited the depression of MC. Our results suggest that treatment with the ET antagonist ETR-P1/fl may be advantageous in the early phase of endotoxemia.

Mucosal permeability changes during intestinal reperfusion injury. The role of mast cells

The objective of this study was to investigate the role of intestinal mast cells in mucosal functional and morphological alterations induced by 30 min segmental ischemia and 120 min reperfusion in anesthetized dogs. The time course of permeability changes of the mucosa to sodium fluorescein (NaFl) in blood-lumen and lumen-blood directions was studied in two separate series of experiments. Local hemodynamics, intramucosal pH (pHi) alterations, mast cell number and degranulation and the degree of tissue injury were determined. The effects of cromolyn (peritoneal-type mast cell stabilizer), quercetin (mucosal-type mast cell stabilizer), and dexamethasone (aspecific membrane stabilizer and mast cell depleter) pretreatments were evaluated. Ischemia-reperfusion induced significant tissue injury, elevated segmental vascular resistance, and decreased pHi. The blood to lumen clearance of NaFl increased significantly during ischemia and reperfusion. Cromolyn and quercetin pretreatment significantly inhibited permeability changes, but did not influence pHi and morphological alterations induced by ischemia-reperfusion. Dexamethasone pretreatment did not influence the number of mast cells, however, the degree of mast cell degranulation and the degree of mucosal damage decreased. These results demonstrate that mast cells or mast cell-induced reactions contribute to the mucosal permeability alterations and barrier lesions during reperfusion, but play a minor role in reperfusion-induced structural injury.

Effects of nitric oxide synthase inhibition on the hemodynamic changes in hyperdynamic endotoxemia

In this study we compared the circulatory effects of the arginine analogue non-specific nitric oxide synthase (NOS) inhibitor N omega-nitro-L-arginine (NNA), and the specific inducible NOS (iNOS) inhibitor S-methylisothiourea (SMT) and S-(2-aminoethyl)-isothiourea (AEST) in a hyperdynamic endotoxemic dog model. Mean arterial pressure (MAP), cardiac output (CO), and myocardial contractility (MC) were measured. A hyperdynamic circulatory response was elicited with a 2-h infusion of a total dose of 5.3 micrograms/kg E. coli endotoxin (ETX). NOS inhibitory treatment (2 mg/kg) was administrated from the 45th min of endotoxemia. ETX induced a hyperdynamic circulatory response, and a significant myocardial depression. NNA induced a prolonged, SMT a transient increase in MC, both drugs elevated MAP, but decreased CO. AEST significantly prolonged the elevation in CO, but did not affect MAP. Selective inhibition of the iNOS may be a beneficial in sepsis.

Investigation of the thoracic electrical impedance during endotoxemia in dogs

The purpose of our study was to examine the effect of sustained low-dose endotoxin infusion on changes in thoracic electrical impedances (Z0 at end-expiratory apnoea, Zmax at end-inspiration), Zmax-Z0, hematocrit (H) values, and extravascular lung water (EVLW) estimated with gravimetrical analysis (WW/DW) and the impedance method (dEVLWimp) in anesthetized dogs. To define the role of H in changes in the Z0 and Zmax, we applied splenectomy. To determine whether changes in respiration might be involved in changes in Z0 and Zmax, mechanically ventilated dogs were examined. During the infusion of endotoxin there was an increase in Z0, Zmax, H and the respiratory rate in the spontaneously breathing dogs. In splenectomized dogs both impedances slightly increased without any significant change in H. In the ventilated dogs Z0 and Zmax increased similarly, and H increased to a slightly lower level than in the spontaneously breathing dogs. In the ventilated-splenectomized dogs no changes were found in the impedances and in H. The EVLW values showed no serious edema in the endotoxemic groups. The results suggest that Z0 increased mainly in association with the increase in H. The Zmax-Z0 parameter proved to be a suitable parameter for demonstrating the changes in respiration.

The cardiac nurse's role: an Australian Delphi study perspective

In Australia, as in many parts of the Western world, technological advances in healthcare have affected the roles of healthcare professionals, including nurses. Cost constraints, efficiency, and effectiveness measures also influence staffing numbers, roles, and skill mix. Specialty nurse education programs are changing, and many are moving from the hospital environment to the higher education sector. Initiatives to introduce the American Advanced Nurse Practitioner role in some environments have begun, although the current advanced practice roles are proving problematic. Specialist professional groups are striving to develop competencies or standards for practice. An understanding of what is required of expert clinicians for practice in complex technological environments such as cardiac care would be useful for both practitioners and academics. A national Delphi study was undertaken to determine what knowledge, skills, and attitudes were required of expert cardiac nurses in relation to technology in the cardiac care environments in both the "real" and the "ideal" worlds of practice. Separate panels of 28 cardiac educators and 42 cardiac nurse clinicians were given a questionnaire of 107 items and asked to indicate on a 6-point Likert scale the importance of each item to the nursing roles in both the "real" and "ideal" worlds. On the final, third round, respondents ranked the three most important items in each of the 13 thematic groups. Overall, the clinicians accepted all 107 items as important to their role, and for the majority of these they, felt that they were performing quite close to their "ideal." This article presents the 32 items for which the clinicians felt the "real" world was quite far from the "ideal" as represented by a gap of > or = 2 between the real and ideal medians. Also, despite being accepted as part of the role through the ideal scores, 21 items achieved a real world median of 3.5 or less, which indicates that in the real world these aspects of nursing are not being valued or practiced to the level clinicians would like. These two sets of items should be of greatest interest to clinicians currently in the role and to those interested in specialty education at all levels.

The role of mast cells in mucosal permeability changes during ischemia-reperfusion injury of the small intestine

The objective of this study was to investigate the significance of mast cell-induced reactions in the mucosal functional and morphological alterations induced by 30 min segmental ischemia and 120 min reperfusion in anesthetized dogs. The rates of changes in permeability of the mucosa to sodium fluorescein (NaFL) in the plasma-to-lumen and lumen-to-plasma directions were studied, the local hemodynamics, intramucosal pH (pHi) alterations, mast cell number and degranulation, and degree of tissue injury were determined. The effects of pretreatments with cromolyn (a peritoneal-type mast cell stabilizer), quercetin (a mucosal-type mast cell stabilizer), and dexamethasone (an aspecific membrane stabilizer and mast cell depleter) were evaluated. We found that ischemia-reperfusion induced significant tissue injury, elevated the segmental vascular resistance, and decreased pHi. The plasma-to-lumen clearance of NaFL increased significantly during ischemia and reperfusion. Cromolyn and quercetin pretreatments significantly inhibited the permeability changes, but did not influence the pHi and morphological alterations induced by ischemia-reperfusion. Dexamethasone pretreatment did not influence the number of mast cells, but the degree of mast cell degranulation and fluorescein leakage decreased. We conclude that intestinal mast cells and mast cell-induced reactions contribute to the mucosal permeability alterations during reperfusion, but play only a minor role in ischemia-reperfusion-induced structural injury.

[Toxoplasmosis diagnosis in pregnancy: computer assisted follow-up interpretation of serologic tests]

Primary infection with Toxoplasma gondii during pregnancy can result in fetal infection with serious sequelae for the unborn if not treated properly. Early diagnosis enables drug therapy and significantly reduces the risk of fetal disease. A systematic serological screening procedure was established in Austria in 1975 to detect primary toxoplasma infection as early as possible during pregnancy. Since the screening program is based solely on observation and interpretation of serological data, the question arises whether a knowledge-based system for automatic interpretation can achieve a sufficient interpretative accuracy for introduction to routine work. For this reason the system Toxopert-I was developed. The system is aimed at facilitating routine laboratory work, as well as assuring quality by setting standards for therapy. The required knowledge base was designed as a knowledge graph, each state representing a certain interpretation. One or more available serological test results cause the knowledge graph to change its current state. If all available test results are processed, the final state reached corresponds to the respective current interpretation for the patient. A retrospective analysis of 1000 pregnant women yielded a total diagnostic sensitivity and specificity of over 99% in comparison with the clinician's diagnosis which was used as the Gold Standard.

Determining and discerning expert practice: a review of the literature

Although the nature and characteristics of expert practice have been described in the literature, the description is incomplete. How expertise is gained is not fully understood, and definitions of expert competencies have yet to be developed. Essential issues for education arise from the demand for knowledge for expert practice. Because expertise is gained in the context of practice, expertise cannot be achieved out of context or taught as an academic exercise. A clear picture of the practice of expert nurses is necessary so that those in the profession can know and articulate expert practice and direct it to the community.

Toxopert-I: knowledge-based automatic interpretation of serological tests for toxoplasmosis

Primary infection with Toxoplasma gondii, a parasite found in most regions of the world, is asymptomatic in more than 80% of cases. However, primary infection with Toxoplasma gondii in a pregnant woman might cause fetal infection and severe damage. Most cases do not require treatment. This applies to women without any infection (denoted as seronegative) and women who have acquired the infection before conception (denoted as latent). In contrast, women with postconceptual infection require immediate treatment to prevent or ameliorate fetal infection. We have developed an expert system, called Toxoport-I, designed for routine laboratory work, which automatically interprets serological test results of toxoplasma infection. By using the system the clinician can also examine questionable cases by interactively exploring possible results. We used a popular method of designing expert systems applied to medical interpretation and therapy advice, the rule-based one. In order to meet the requirements of automatic interpretation in toxoplasma serology the following characteristics were introduced: the interpretation of sequences of test results, the possibility of excluding inconsistent test results and the adaptability of the knowledge base. A decision graph that covers the different kinds of infections as well as therapy and recommendations for further tests was designed, implemented and was clinically tested by carrying out a retrospective study including 1000 pregnant women. A comparison of Toxoport-I and the clinician's interpretations yielded sensitivity and specificity rates of over 99% each.

Possible relationship between histamine and nitric oxide release in the postischemic flow response following mesenteric ischemia of different durations

During the postischemic flow response (PFR), vasodilator mediators such as nitric oxide (NO) and histamine are liberated, influencing the blood flow rate at the onset of reperfusion. The possible roles of these two mediators, and the relationship between their release, were examined during segmental intestinal ischemia of different durations and subsequent reperfusion in two series of anesthetized dogs. In series I (untreated ischemia), 15, 30, 60, and 120 min ischemia and 2 h reperfusion were studied. In series II, the same experimental protocol was repeated after pretreatment with the NO synthase inhibitor N-nitro-L-arginine (NNA, 10 mumol/kg, i.e., 2.19 mg/kg). Intramucosal pH (pHi), segmental blood flow and effluent histamine levels were measured, and segmental vascular resistance (SVR) and PFR volumes were calculated. The ischemic periods caused a considerable fall in pHi. Reperfusion resulted in an early return to normal pHi levels following a 15 or 30 min ischemia, but this process took longer after longer occlusions. In the later phase of reperfusion, SVR was elevated. The PFR volume increased in proportion to the duration of occlusion, except after the 120 min ischemia. At the onset of reperfusion, peak histamine levels rose in parallel with the duration of ischemia. During reperfusion, a prolonged decrease in pHi, an increase in SVR, and a reduction in PFR volume, with no significant histamine level elevation, were observed in the NNA-treated groups. This study indicates that both NO and histamine take part in the PFR in the canine small intestine. Inhibition of NO synthesis prevents the postischemic release of histamine.