Effects of ultra-high field MRI environment on cognitive performance in healthy participants

INTRODUCTION

Ultra-high field MRI (UHF MRI) is rapidly becoming an essential part of our toolbox within health care and research studies; therefore, we need to get a deeper understanding of the physiological effects of ultra-high field. This study aims to investigate the cognitive performance of healthy participants in a 7 T (T) MRI environment in connection with subjectively experienced effects.

METHODS

We measured cognitive performance before and after a 1-h 7T MRI scanning session using a Digit Symbol Substitution Test (DSST) in 42 subjects. Furthermore, a computer-based survey regarding the subjectively experienced effects in connection with the MRI examination was distributed. Similarly, two DSSTs were also performed by a control group of 40 participants.

RESULTS

Even though dizziness was the strongest sensory perception in connection to the MRI scanning, we did not find any correlation between dizziness and cognitive performance. Whilst the control group improved (p=<0.001) on their second DSST the MRI group showed no significant difference (p=0.741) in the DSST before and after MRI scanning.

CONCLUSION

Transient effect on cognition after undergoing MRI scanning can't be ruled out as the expected learning effect on the DSST was not observed.

IMPLICATIONS FOR PRACTICE

Increasing understanding of the possible adverse effects may guide operators in performing UHF MRI in a safe way and with person-centered care. Furthermore, it can guide researchers in setting up research protocols to minimize confounding factors in their fMRI studies due to the transient adverse effects of the UHF environment.

Cognitive performance in systemic lupus erythematosus patients: a cross-sectional and longitudinal study

Background

Previous research has provided evidence for cognitive dysfunction as a common symptom of systemic lupus erythematosus (SLE). In light of this, the primary goal of this study was to investigate how cognitive impairment in this patient group develops over time. In addition, the present dataset contributes to delineating the specific abilities that are impaired in SLE patients as well as answering the question whether the disease affects the cognition of SLE patients with neuropsychiatric manifestations (NPSLE) and without (non-NPSLE) in distinct ways.

Methods

91 female participants (33 NPSLE, 29 non-NPSLE, 29 healthy controls (HC)) underwent standardized neurocognitive testing. A total of ten different cognitive abilities were assessed, among others executive function, memory, and attention. Some of the participants (30 NPSLE patients, 22 non-NPSLE, 13 HC) were tested twice (mean time between testing sessions: 50 months) to enable longitudinal tracking of cognitive abilities. Analyses of Variance (ANOVA) were conducted to determine whether cognitive performance differed cross-sectionally between the groups. Linear mixed effects models were fit to investigate performance differences between the groups over time.

Results

Cross-sectional analysis at follow-up demonstrated that the cognitive performance of both NPSLE and non-NPSLE was significantly lower than that of HC for the motor speed and the psychomotor speed domain. Additionally, NPSLE patients performed significantly weaker than HC in the complex attention domain. At the same time, the cross-sectional data did not yield any support for performance differences between NPSLE and non-NPSLE patients. Weak positive correlations between disease duration and psychomotor speed, motor speed and reaction time emerged. A temporal progression of cognitive dysfunction in SLE patients was not confirmed.

Conclusions

Cognitive performance is affected in both non-NPSLE and NPSLE patients. However, a linear decline in performance over time could not be verified. More in-depth longitudinal assessments of cognition in SLE patients are needed to establish how cognitive abilities in this patient population develop over time.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41927-022-00253-3.

Direct oral anticoagulant use and risk of severe COVID-19

BACKGROUND

Hypercoagulability and thromboembolism are prominent features of severe COVID-19, and ongoing anticoagulant use might be protective.

METHODS

We conducted a nationwide register-based cohort study in Sweden, February through May, 2020, to assess whether ongoing direct oral anticoagulant (DOAC) use was associated with reduced risk of hospital admission for laboratory-confirmed COVID-19, or a composite of intensive care unit (ICU) admission or death due to laboratory-confirmed COVID-19.

RESULTS

DOAC use (n = 103 703) was not associated with reduced risk of hospital admission for COVID-19 (adjusted hazard ratio [aHR] [95% confidence interval] 1.00 [0.75-1.33] vs. nonuse atrial fibrillation comparator [n = 36 875]; and aHR 0.94 [0.80-1.10] vs. nonuse cardiovascular disease comparator [n = 355 699]), or ICU admission or death due to COVID-19 (aHRs 0.76 [0.51-1.12], and 0.90 [0.71-1.15], respectively).

CONCLUSION

Ongoing DOAC use was not associated with reduced risk of severe COVID-19, indicating that prognosis would not be modified by early outpatient DOAC initiation.

Autonomic modulation networks in schizophrenia: The relationship between heart rate variability and functional and structural connectivity in the brain

Heart rate variability (HRV), a measurement of autonomic nervous system (ANS) activity, has been found reduced in schizophrenia. The anterior cingulate cortex (ACC), which is important in regulating the ANS, is structurally and functionally affected in schizophrenia. We investigate the relationship between HRV and functional and structural connectivity of the ACC in patients with schizophrenia and healthy controls. Ten patients with a diagnosis of schizophrenia and ten healthy controls were recruited. Heart rate was monitored in a naturalistic out-of-clinic setting. Magnetic resonance imaging (MRI) was performed, including resting-state functional MRI and diffusion tensor imaging. Patients with schizophrenia had significantly lower HRV compared to controls. A positive correlation between ACC connectivity with the bilateral cerebellum and HRV was found in the patients. HRV was also positively correlated with amplitude of low frequency fluctuations (ALFF) in the cerebellum, and with axial diffusivity in the middle cerebellar peduncle, in the patients. There was a significant negative relationship between antipsychotic medication dosage, HRV and all neuroimaging measures related to HRV. We conclude that ACC connectivity seems to be affected in schizophrenia, both structurally and functionally, and that the ACC-cerebellum connectivity, as well as cerebellar function, is associated with ANS regulation in patients with schizophrenia.

Assessment of agreement and interchangeability between the TEG5000 and TEG6S thromboelastography haemostasis analysers: a prospective validation study

Background

TEG6S® and TEG5000® (Haemonetics Corp, USA) are haemostasis analysers that measure viscoelasticity properties of whole blood. Both use different mechanisms to assess similar components of the coagulation process. The aim of this study was to assess agreement and interchangeability between the TEG6S and TEG5000 analysers.

Methods

3.5 mL whole blood was collected from 25 adult patients in a tertiary intensive care unit (ICU). Analysis was performed using TEG6S and TEG5000 haemostatic platforms. Agreement between platforms was measured using Lin’s concordance coefficient (Lin’s CC), further validated using intraclass correlation coefficients and reduced major axis regression (RMAR).

Results

Sixteen (64%) patients were male; mean (range) age: 59yo (23–86). TEG6S and TEG5000 systems were broadly interchangeable. The majority of TEG variables demonstrated almost perfect or substantial agreement and minimal proportional bias (maximum amplitude demonstrated a fixed bias). LY30%, however, demonstrated poor agreement and a proportional bias. Lin’s CC coefficients (95% CI, RMAR slope, intercept) between TEG6S and TEG5000 variables were: R time: 0.78 (0.64–0.92, 0.76, 0.92); K time: 0.82 (0.69–0.94, 1.30, − 0.93); alpha angle: 0.79 (0.64–0.95, 1.04, − 1.43); maximum amplitude (MA): 0.90 (0.83–0.96, 0.99, − 5.0); LY30%: 0.34 (0.1–0.58, 0.43, 0.04).

Conclusions

Adult patients with critical illness demonstrate almost perfect agreement in the R time and MA, substantial agreement in K time and alpha angle, but poor agreement in LY30%, as measured by the TEG6S and TEG5000 analysers. With the exception of LY30%, the TEG6S and TEG5000 platforms appear interchangeable. This has important implications for use in clinical practice and multi-site research programs.

Trial registration

ANZCRT number: 12617000062325, registered 12/Jan17. Retrospectively registered.

Electronic supplementary material

The online version of this article (10.1186/s12871-019-0717-7) contains supplementary material, which is available to authorized users.

White matter lesions and brain atrophy in systemic lupus erythematosus patients: correlation to cognitive dysfunction in a cohort of systemic lupus erythematosus patients using different definition models for neuropsychiatric systemic lupus erythematosus

Aim

The aim of this study was to evaluate the extent of white matter lesions, atrophy of the hippocampus and corpus callosum, and their correlation with cognitive dysfunction (CD), in patients diagnosed with systemic lupus erythematosus (SLE).

Methods

Seventy SLE patients and 25 healthy individuals (HIs) were included in the study. To evaluate the different SLE and neuropsychiatric SLE (NPSLE) definition schemes, patients were grouped both according to the American College of Rheumatology (ACR) definition, as well as the more stringent ACR-Systemic Lupus International Collaborating Clinics definition. Patients and HIs underwent a 3 Tesla brain MRI and a standardized neuropsychological test. MRI data were evaluated for number and volume of white matter lesions and atrophy of the hippocampus and corpus callosum. Differences between groups and subgroups were evaluated for significance. Number and volume of white matter lesions and atrophy of the hippocampus and corpus callosum were correlated to cognitive dysfunction.

Results

The total volume of white matter lesions was significantly larger in SLE patients compared to HIs ( p = 0.004). However, no significant differences were seen between the different SLE subgroups. Atrophy of the bilateral hippocampus was significantly more pronounced in patients with NPSLE compared to those with non-NPSLE (right: p = 0.010; left p = 0.023). Significant negative correlations between cognitive test scores on verbal memory and number and volume of white matter lesions were present.

Conclusion

SLE patients have a significantly larger volume of white matter lesions on MRI compared to HIs and the degree of white matter lesion volume correlates to cognitive dysfunction, specifically to verbal memory. No significant differences in the number or volume of white matter lesions were identified between subgroups of SLE patients regardless of the definition model used.

Assessment of plasma endostatin to predict acute kidney injury in critically ill patients

BACKGROUND

We evaluated whether plasma endostatin predicts acute kidney injury (AKI), need for renal replacement therapy (RRT), or death.

METHODS

Prospective, observational, multicenter study from 1 September 2011 to 1 February 2012 with data from 17 intensive care units (ICUs) in Finland.

RESULTS

A total of 1112 patients were analyzed. We measured plasma endostatin within 2 h of ICU admission. Early AKI (KDIGO stage within 12 h of ICU admission) was found in 20% of the cohort, and 18% developed late AKI (KDIGO criteria > 12 h from ICU admission). Median (IQR) admission endostatin was higher in the early AKI group, 29 (19.1, 41.9) ng/ml as compared to 22.4 (16.1, 30.1) ng/ml for the late AKI group, and 18 (14.0, 23.6) ng/ml for non-AKI patients (P < 0.001). Endostatin level increased with increasing KDIGO stage. Significantly higher endostatin levels were found in patients with sepsis as compared to those without. Predictive properties for AKI, RRT, and mortality were low with corresponding areas under the receiver operating characteristic curve (AUC) of 0.62, 0.67, and 0.59. Sensitivity analyses among patients with chronic kidney disease or sepsis did not improve the predictive ability of endostatin. Adding endostatin to a clinical AKI prediction model (illness severity score, urine output, and age) insignificantly changed the AUC from 0.67 to 0.70 (P = 0.14).

CONCLUSIONS

Endostatin increases with AKI severity but has limited value as a predictor of AKI, RRT and 90-day mortality in patients admitted to ICU. Moreover, endostatin does not improve AKI risk prediction when added to a clinical risk model.

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine: Brussels, Belgium. 15-18 March 2016

[This corrects the article DOI: 10.1186/s13054-016-1208-6.].

Association between fluid balance and mortality in patients with septic shock: a post hoc analysis of the TRISS trial

BACKGROUND

Several studies have shown an association between a positive fluid balance and increased mortality in patients with septic shock. This may have led to a more restrictive use of intravenous fluids. The association between fluid accumulation and mortality in the setting of a more restrictive use of intravenous fluids, however, is uncertain. We therefore aimed to investigate the association between a cumulative fluid balance 3 days after randomization and 90-day mortality in a recent Nordic multicentre cohort of patients with septic shock.

METHODS

A post hoc analysis of patients from the Transfusion Requirements in Septic Shock (TRISS) trial treated for 3 days or more in the ICU after randomization. The patients were categorized into four groups depending on their weight-adjusted cumulative fluid balance after 3 days. We performed multivariable Cox regression analysis, adjusting for important prognostics (study site, age, chronic cardiovascular and chronic lung disease, haematologic malignancy, chronic dialysis, source of infection, baseline SOFA score and plasma lactate).

RESULTS

The median cumulative fluid balance of the 841 included patients was 2480 ml (IQR 47-5045). The median time from ICU admission to inclusion in the trial was 22 h. The overall 90-day mortality was 52%. There was no statistically significant association between fluid balance 3 days from inclusion and 90-day mortality after the adjustment for the prognostics (P = 0.37).

CONCLUSION

In our cohort of patients with septic shock and a comparably low cumulative fluid balance, there was no association between fluid balance and mortality. However, the study design and the limited power preclude strong conclusions. There is an urgent need for high-quality trials assessing the benefit and harm of different fluid volume strategies in patients with septic shock.

Urinary neutrophil gelatinase-associated lipocalin to hepcidin ratio as a biomarker of acute kidney injury in intensive care unit patients

BACKGROUND

Labile iron is important in the pathogenesis of acute kidney injury (AKI). Neutrophil gelatinase-associated lipocalin (NGAL) and hepcidin control iron metabolism and are upregulated during renal stress. However, higher levels of urinary NGAL are associated with AKI severity whereas higher urinary hepcidin levels are associated with absence of AKI. We aimed to investigate the value of combining both biomarkers to estimate the severity and progression of AKI in intensive care unit (ICU) patients.

METHODS

Urinary NGAL and hepcidin were quantified within 48 hours of ICU admission in patients with the systemic inflammatory response syndrome and early kidney dysfunction (oliguria for ≥ 2 hours and/or a 25 µmol/L creatinine rise from baseline). Diagnostic and prognostic characteristics were assessed by logistic regression and receiver operating characteristics (ROC) analysis.

RESULTS

Of 102 patients, 26 had mild AKI and 28 patients had severe AKI on admission. Sepsis (21%), cardiac surgery (17%) and liver failure (9%) were primary admission diagnoses. NGAL increased (P=0.03) whereas hepcidin decreased (P=0.01) with increasing AKI severity. The value of NGAL/hepcidin ratio to detect severe AKI was higher than when NGAL and hepcidin were used individually and persisted after adjusting for potential confounders (adjusted OR 2.40, 95% CI 1.20-4.78). The ROC areas for predicting worsening AKI were 0.50, 0.52 and 0.48 for NGAL, 1/hepcidin and the NGAL/hepcidin ratio.

CONCLUSION

The NGAL/hepcidin ratio is more strongly associated with severe AKI than the single biomarkers alone. NGAL and hepcidin, alone or combined as a ratio, were unable to predict progressive AKI in this selected ICU cohort.

Photophysics and ex vivo biodistribution of β-cyclodextrin-meso-tetra(m-hydroxyphenyl)porphyrin conjugate for biomedical applications

Photophysics andex vivobiodistribution of porphyrin (meso-tetra(m-hydroxyphenyl)porphyrin;mTHPP) and porphyrin-cyclodextrin conjugate (β-cyclodextrin-meso-tetra(m-hydroxyphenyl)porphyrin; CD-mTHPP) were investigated and compared.

Heart failure at home—patients’ experiences of participation in structured home care

Introduction

Aim

Methods

Heart failure at home—an observational study of participation among patients in structured home care

Introduction

Aim

Methods

Occurrence of adult Fanconi syndrome in benign monoclonal gammopathy

Adult Fanconi syndrome has been described as a manifestation of a latent form of myeloma. Since benign monoclonal gammopathy (BMG) is a latent form of myeloma we studied ten patients with this disease with respect to the adult Fanconi syndrome. These patients were selected from a larger group with BMG because of urinary excretion of monoclonal light chains. In no instance could a complete Fanconi syndrome be shown, but one patient, who also had a diabetic nephropathy, had very high levels of urinary beta 2-microglobulins. Two additional patients showed minor features included in the adult Fanconi syndrome. BMG does not seem to be associated with an increased risk of developing adult Fanconi syndrome.

Urinary excretion of inorganic sulfate, ester sulfate, total sulfur and taurine in cancer patients

The urinary excretion of inorganic sulfate, ester sulfate, taurine and total sulfur has been estimated in 18 patients with malignancy, and compared with those of an age-matched reference group. The absolute amount of inorganic sulfate was significantly lower in the cancer group, whereas an increased ester sulfate excretion was observed. Reduced excretion of total sulfate (inorganic plus ester sulfate) and increased excretion of "neutral sulfur" (total sulfur minus total sulfate) in the cancer group was calculated from these data. If these values were recalculated with respect to creatinine, no significant differences were found for inorganic and total sulfate between the two patient groups, whereas ester sulfate and the "neutral sulfur" fractions were still increased. The enlarged "neutral sulfur" could to a large extent be explained by an increased excretion of taurine. The mechanism behind these findings is discussed.

Heart failure management programmes in Europe

BACKGROUND

The ESC guidelines recommend that an organised system of specialist heart failure (HF) care should be established to improve outcomes of HF patients. The aim of this study was therefore to identify the number and the content of HF management programmes in Europe.

METHOD

A two-phase descriptive study was conducted: an initial screening to identify the existence of HF management programmes; and a survey to describe the content in countries where at least 30% of the hospitals had a programme.

RESULTS

Of the 43 European countries approached, 26 (60%) estimated the percentage of HF management programmes. Seven countries reported that they had such programmes in more than 30% of their hospitals. Of the 673 hospitals responding to the questionnaire, 426 (63%) had a HF management programme. Half of the programmes (n = 205) were located in an outpatient clinic. In the UK a combination of hospital and home-based programmes was common (75%). The most programmes included physical examination, telephone consultation, patient education, drug titration and diagnostic testing. Most (89%) programmes involved nurses and physicians. Multi-disciplinary teams were active in 56% of the HF programmes. The most prominent differences between the 7 countries were the degree of collaboration with home care and GP's, the role in palliative care and the funding.

CONCLUSION

Only a few European countries have a large number of organised programmes for HF care and follow up. To improve outcomes of HF patients throughout Europe more effort should be taken to increase the number of these programmes in all countries.

Situations influencing habits in diet and exercise among nurses working night shift

OBJECTIVES

The aim of the investigation was to describe situations with a significant influence on healthy diet and exercise habits among nurses working night shift.

METHODS

A qualitative descriptive design with a Critical Incident Technique approach was used. Situations were collected by means of interviews with 27 registered/enrolled community nurses.

RESULTS

A total of 143 situations were identified comprising two main areas: coping ability at work and coping ability during leisure hours. Coping ability at work included 81 critical incidents grouped into two categories: the nurses' diet and exercise habits were influenced by social interaction with colleagues at work and by the disruption to their circadian rhythm. Coping ability during leisure hours included 62 critical incidents grouped into two categories: the diet and exercise habits were influenced when the nurses recovered from the disruption to their circadian rhythm and when they took advantage of the freedom of action offered by night work.

CONCLUSIONS

By identifying the factors that influence diet and exercise habits among nurses working night shift, strategies can be developed in order to strengthen the factors with a positive influence.

Patients with heart failure in primary health care: effects of a nurse-led intervention on health-related quality of life and depression

AIMS

To determine the effects of a nurse-led intervention designed to improve self-management of patients with heart failure in a primary health care setting regarding health-related quality of life and depression.

METHODS

Patients at eight primary health care centres were screened by the Diagnosis Related Groups registry for the diagnosis of heart failure and eligibility for a cluster randomised study. A total of 153 patients were included (n=78 in the intervention group, 54% males, mean age 79 years, 59% in New York Heart Association class III-IV). The intervention involved patient and family education about heart failure and self-management and monthly telephone follow-up during 12 months by a primary health care nurse.

RESULTS

The effects of the nurse-led intervention were limited. Significant differences were found in the physical dimension measured by the SF-36 health survey, and in depression measured by the Zung Self-rating Depression Scale. In comparison within groups at the 3 and 12-month follow-up, the intervention group significantly maintained their health-related quality of life measured by the SF-36 health survey, and their experience of depression measured by the Zung Self-rating Depression Scale to a greater extent than in the control group, especially among women.

CONCLUSION

A nurse-led intervention directed toward patients with heart failure in a primary health care setting resulted in limited effects between the groups, although the physical and mental status were retained during 12 months of follow-up to a greater extent than in the control group.

A novel nonsense mutation of the mineralocorticoid receptor gene in a Swedish family with pseudohypoaldosteronism type I (PHA1)

Pseudohypoaldosteronism type I (PHA1) is a condition associated with salt wasting leading to dehydration, hypotension, hyperkalemia, and metabolic acidosis. Sporadic cases and two familial forms, one autosomal dominant and one autosomal recessive form, have been described. The autosomal dominant or sporadic form manifests milder salt wasting that remits with age. Mutations in the gene encoding the mineralocorticoid receptor (MR) have been identified in patients with the autosomal dominant inheritance. However, recent studies suggest that the autosomal dominant and sporadic forms are genetically heterogeneous and that additional genes might be involved. We report on the study of 15 members of a Swedish five-generation family with the autosomal dominant form of PHA1. Interestingly, neuropathy was found in two of five affected individuals. A novel heterozygous nonsense mutation C436X in exon 2 was identified in the index patient by linkage analysis, PCR, and direct sequencing of the MR gene. Analysis of the family demonstrated that the mutation segregated with PHA1 in the family. It is unclear whether the neuropathy is associated with the mutation found. Our results together with previously published data suggest that loss-of-function mutations of the MR gene located at 4q31.1, commonly are associated with the autosomal dominant form of PHA1.

Development and testing of the European Heart Failure Self-Care Behaviour Scale

BACKGROUND

Improvement of self-care behaviour is an aim of several non-pharmacological nurse-led management programmes for patients with heart failure. These programmes are often evaluated based on their effects on readmission, costs and quality of life. It is, however, also important to know how patients changed their self-care behaviour as a result of such a programme. Therefore a comprehensive, reliable and valid measure of the self-care behaviour of HF patients is needed.

OBJECTIVES

To develop a scale measuring the behaviour that heart failure patients perform to maintain life, healthy functioning, and well-being.

METHOD

The European Heart Failure Self-Care Behaviour Scale (EHFScBS) was developed in three phases: (1) concept analysis and first construction; (2) revision of items and response and scoring format; and (3) testing of the new scale for validity and reliability.

RESULTS

The European Heart Failure Self-Care Behaviour Scale is a 12-item, self-administered questionnaire that covers items concerning self-care behaviour of patients with heart failure. Face-validity and concurrent validity was established and the internal consistency of the scale was tested using pooled data of 442 patients from two centres in Sweden, three in the Netherlands and one in Italy. Cronbachs's alpha was 0.81.

CONCLUSION

The instrument is a valid, reliable and practical scale to measure the self-reported self-care behaviour of heart failure patients. It is ready to use by investigators evaluating the outcome of heart failure management programmes that target changes in patients' self-care practices.

Nurse-led heart failure clinics improve survival and self-care behaviour in patients with heart failure: results from a prospective, randomised trial

AIM

The aim of this trial was to prospectively evaluate the effect of follow-up at a nurse-led heart failure clinic on mortality, morbidity and self-care behaviour for patients hospitalised due to heart failure for 12 months after discharge.

METHODS

A total of 106 patients were randomly assigned to either follow-up at a nurse-led heart failure clinic or to usual care. The nurse-led heart failure clinic was staffed by specially educated and experienced cardiac nurses, delegated the responsibility for making protocol-led changes in medications. The first follow-up visit was 2-3 weeks after discharge. During the visit the nurse evaluated the heart failure status and the treatment, gave education about heart failure and social support to the patient and his family.

RESULTS

There were fewer patients with events (death or admission) after 12 months in the intervention group compared to the control group (29 vs 40, p=0.03) and fewer deaths after 12 months (7 vs 20, p=0.005). The intervention group had fewer admissions (33 vs 56, p=0.047) and days in hospital (350 vs 592, p=0.045) during the first 3 months. After 12 months the intervention was associated with a 55% decrease in admissions/patient/month (0.18 vs 0.40, p=0.06) and fewer days in hospital/patient/month (1.4 vs 3.9, p=0.02). The intervention group had significantly higher self-care scores at 3 and 12 months compared to the control group (p=0.02 and p=0.01).

CONCLUSIONS

Follow up after hospitalisation at a nurse-led heart failure clinic can improve survival and self-care behaviour in patients with heart failure as well as reduce the number of events, readmissions and days in hospital.

Suppression of nonlinear effects by phase alternation in strongly dispersion-managed optical transmission

The nonlinear effects of amplitude jitter and ghost pulse generation, which are present in strongly dispersion-managed optical communication systems can be suppressed by alternation of the phase of the bits. A physical explanation for this effect is given that shows that with suitably chosen phase modulations the processes that give rise to the nonlinear effects will counteract each other.

Control of electron transfer in supramolecular systems

The fluorescence quantum yield of zinc porphyrin (ZnP) covalently linked to 9,10-bis(phenylethynyl)anthracene (AB) is strongly dependent upon the solvent properties. The bichromophoric system ZnP-AB exhibits 'normal' zinc porphyrin fluorescence in solvents that cannot coordinate to the central zinc atom. In contrast, if a Lewis base, such as pyridine, is added to a sufficiently polar solvent, the fluorescence is significantly quenched. Picosecond transient absorption measurements, in conjunction with fluorescence quenching and cyclic voltammetric measurements, suggest that the quenching mechanism is intramolecular electron transfer from ZnP to AB. The charge separated state. ZnP*+-AB*-, has a lifetime of not more than 220 ps before recombining. If a secondary electron acceptor, iron(III) porphyrin (FeP), is covalently connected to the AB unit, a second electron transfer from AB*- to FeP occurs and the charge separated state, ZnP*+-AB-FeP*-, has a lifetime of at least 5 ns. This demonstrates that electron transfer might be sensitively tuned (switched on) by specific solvent effects.

Possibility to deduce the emission time sequence of neutrons and protons from the neutron-proton correlation function

Experimental information has been derived from the neutron-proton correlation function in order to deduce the time sequence of neutrons and protons emitted at 45 degrees in the E/A = 45 MeV 58Ni + 27Al reaction.

Decisive situations influencing spouses' support of patients with heart failure: a critical incident technique analysis

OBJECTIVE

The aim of this study was to describe decisive situations experienced by spouses of patients with heart failure that could potentially affect their ability to provide social support to the patient.

METHODS

A qualitative descriptive design with a critical incident technique was used. Twenty-three informants, 15 women and 8 men, who were spouses of patients with severe heart failure were strategically chosen to ensure maximal variation in sociodemographic data and experiences as a spouse.

RESULTS

Decisive situations influenced the experience of spouses of patients with heart failure in a manner that was either positive (involvement with others) or negative (feeling like an outsider). When spouses were given attention and treated like persons of value, they experienced involvement with others. In these cases, spouses had someone to turn to and were included in the physical care. In contrast, when spouses were kept at a distance by the patient, were socially isolated, and received insufficient support from children, friends, and health care professionals, they experienced feeling like an outsider.

CONCLUSIONS

By identifying spouses' experiences, health care professionals can assess which kind of specific interventions should be used to improve the life situation of the patient with heart failure and his or her spouse.

Generation and dynamics of ghost pulses in strongly dispersion-managed fiber-optic communication systems

We investigate the nonlinear generation and dynamics of ghost pulses in high-speed strongly dispersion-managed fiber-optic communication systems. Particular consideration is given to the importance of system parameters for the properties of the emerging ghost pulses. Conclusions are drawn about the growth rate and the temporal position of the ghost pulses in different systems.

Enhanced intersystem crossing in donor/acceptor systems based on zinc/iron or free-base/iron porphyrins

The deactivation pathways of the singlet excited state of a series of zinc or free-base donor porphyrins covalently linked by a bridge to a paramagnetic iron(III) chloride porphyrin acceptor have been studied. These donor-bridge-acceptor systems all share a similar geometry (25 A donor-acceptor center-to-center distance), but the bridges vary in electronic structure. In previously reported investigations of zinc/iron porphyrin systems, the fluorescence quenching of the donor has predominantly been assigned to electron transfer. However, for the porphyrin systems studied in this paper, we show that the dominant deactivation channels are enhanced intersystem crossing and singlet energy transfer. In both series, the intersystem crossing rate (S1-->T1) of the donor moiety is almost doubled in the presence of a paramagnetic high-spin metal-porphyrin acceptor. The significant spectral overlap of the donor fluorescence and acceptor absorption in both series allows for efficient singlet energy transfer (Forster mechanism). Furthermore, the bridging chromophores mediate energy transfer and the enhancement is inversely dependent upon the energy gap between the donor and bridge excited states. Although Marcus theory predicts thermodynamically favorable electron transfer to occur in the systems investigated, the quenching rate constants were found to be independent of solvent polarity, and no charge-separated state could be detected, indicating very small electronic coupling for electron transfer.

Bridge-dependent electron transfer in porphyrin-based donor-bridge-acceptor systems

Photoinduced electron transfer in donor-bridge-acceptor systems with zinc porphyrin (or its pyridine complex) as the donor and gold(III) porphyrin as the acceptor has been studied. The porphyrin moieties were covalently linked with geometrically similar bridging chromophores which vary only in electronic structure. Three of the bridges are fully conjugated pi-systems and in a fourth, the conjugation is broken. For systems with this bridge, the quenching rate of the singlet excited state of the donor was independent of solvent and corresponded to the rate of singlet energy transfer expected for a Förster mechanism. In contrast, systems with a pi-conjugated bridging chromophore show a solvent-dependent quenching rate that suggests electron transfer in the Marcus normal region. This is supported by picosecond transient absorption measurements, which showed formation of the zinc porphyrin radical cation only in systems with pi-conjugated bridging chromophores. On the basis of the Marcus and Rehm-Weller equations, an electronic coupling of 5-20 cm(-)(1) between the donor and acceptor is estimated for these systems. The largest coupling is found for the systems with the smallest energy gap between the donor and bridge singlet excited states. This is in good agreement with the coupling calculated with quantum mechanical methods, as is the prediction of an almost zero coupling in the systems with a nonconjugated bridging chromophore.

Timing jitter owing to intrachannel pulse interactions in dispersion-managed transmission systems

We study interaction-induced timing jitter in single-channel dispersion-managed return-to-zero ttransmission systems operating at high map strengths. An equation for the frequency and timing shifts of two interacting pulses is derived by a variational approach. The interaction can be of either an attractive or a repulsive character, and we show that the resultant timing jitter can be reduced by proper design of the dispersion map.

Nurse-led heart failure clinics in Sweden

OBJECTIVE

The aim of this study was to describe the nurse-led heart failure care in Sweden.

METHODS

A postal questionnaire was sent to all 86 hospitals in Sweden treating heart failure patients. All hospitals completed the questionnaire, which contained 20 questions about heart failure nurses, patient education, heart failure clinics, co-operation with primary healthcare and care programmes.

RESULTS

Sixty-nine percent of all hospitals (n=86) had nurses specialised in taking care of heart failure patients, in total 148 heart failure nurses. The nurses were involved in patient education and follow-up. There were nurse-led heart failure clinics in 66% of the hospitals. The clinics provided follow-up after hospitalisation, telephone counselling and drug titration. The majority of the heart failure nurses had been delegated the responsibility for making protocol-led changes in medications. Most clinics registered the number of annual visits to the clinic, and the largest clinic had up to 1000 visits. Approximately half of the hospitals had a special care plan for patients with heart failure and an organised co-operation with primary healthcare.

CONCLUSION

The first nurse-led heart failure clinic started in Sweden in 1990 and since then the model has been spread to two-thirds of the Swedish hospitals.

Towards an artificial model for Photosystem II: a manganese(II,II) dimer covalently linked to ruthenium(II) tris-bipyridine via a tyrosine derivative

In order to model the individual electron transfer steps from the manganese cluster to the photooxidized sensitizer P680+ in Photosystem II (PS II) in green plants, the supramolecular complex 4 has been synthesized. In this complex, a ruthenium(II) tris-bipyridine type photosensitizer has been linked to a manganese(II) dimer via a substituted L-tyrosine, which bridges the manganese ions. The trinuclear complex 4 was characterized by electron paramagnetic resonance (EPR) and electrospray ionization mass spectrometry (ESI-MS). The excited state lifetime of the ruthenium tris-bipyridine moiety in 4 was found to be about 110 ns in acetonitrile. Using flash photolysis in the presence of an electron acceptor (methylviologen), it was demonstrated that in the supramolecular complex 4 an electron was transferred from the excited state of the ruthenium tris-bipyridine moiety to methylviologen, forming a methylviologen radical and a ruthenium(III) tris-bipyridine moiety. Next, the Ru(III) species retrieved the electron from the manganese(II/II) dimer in an intramolecular electron transfer reaction with a rate constant kET > 1.0 x 10(7) s(-1), generating a manganese(II/III) oxidation state and regenerating the ruthenium(II) photosensitizer. This is the first example of intramolecular electron transfer in a supramolecular complex, in which a manganese dimer is covalently linked to a photosensitizer via a tyrosine unit, in a process which mimics the electron transfer on the donor side of PS II.

Patients with implantable cardioverter-defibrillators and their conceptions of the life situation: a qualitative analysis

The implantable cardioverter-defibrillator (ICD) is today widely used for the treatment of sudden cardiac near-death episodes as a result of malignant ventricular dysrhythmia. After examining the literature, only four descriptive studies, all carried out in the USA, with a qualitative analysis based on ICD-patients' own perspectives on their life situation have been found. The aim of this study was to describe how patients living with an ICD-device in south-western Sweden conceive their life situation. As the focus was on patients' conceptions seen from a holistic perspective, an analysis inspired by phenomenography was employed on a strategic sample of 15 ICD-patients. Six categories emerged: a feeling of safety, a feeling of gratitude, a feeling of being, having a network, having a belief in the future, and gaining awareness. Although the findings cannot be generalized because of the descriptive research design, they illuminate the beneficial as well as intrusive effects of such a device, and emphasize the need for support groups for patients and families as well as further education for personnel in hospital and primary health care.

Female patients with congestive heart failure: how they conceive their life situation

Congestive heart failure (CHF) is a significant health problem for women, particularly elderly women. The risk factors for heart failure appear to be different in women than in men, with hypertension and diabetes playing a greater role in women and ischaemic heart disease a greater role in men. The aim of this study was to describe, from a nurse's perspective, how female patients with CHF conceive their life situation. Interview questions were designed with a focus on five dimensions: biophysical, socio-cultural, emotional, intellectual and spiritual-existential. A qualitative method was used with a phenomenographic approach, as this approach examines aspects of the surroundings as they are conceived. Five categories emerged in the results: feeling content, feeling a sense of support, feeling a sense of limitation, feeling anxiety and feeling powerless. A sense of limitation regarding working capacity and being able to support those in their surroundings causes patients with CHF to experience anxiety due to feeling insecure about themselves and in relation to their surroundings. This may result in feelings of worthlessness in women with CHF, both concerning their own capacity and the fact that they feel they are a burden to those around them. Through nursing intervention, these patients can receive help to break this vicious circle of feeling limited and powerless. This can be done by encouraging them to verbalize their feelings and set realistic goals and expectations, and by increasing their knowledge and that of their families concerning CHF and its symptoms, with a focus on self-care and existing possibilities. These measures will make it easier for women with CHF to maintain a hopeful perspective and a sense of control, competence, and self-esteem.

Chromium-51-EDTA clearance in adults with a single-plasma sample

In 1996, a committee on renal clearance recommended a mean sojourn time-based methodology for single-sample determination of plasma clearance of 99mTc-diethylenetriamine pentaacetic acid (DTPA) to be used on adults if the patient's glomerular filtration rate (GFR) is suspected to be >30 ml/min. The main purpose of this study was to derive a mean sojourn time-based formula for calculation of 51Cr-ethylenediamine tetraacetic acid (EDTA) clearance in adults.

METHODS

Two groups of patients with 51Cr-EDTA clearance (Cl) between 16 and 172 ml/min were studied. In Group I (n = 46), reference Cl was determined as a multiplasma sample, single-injection method (ClSM). Sixteen blood samples were drawn from 0 until 5 hr after a single intravenous injection of 51Cr-EDTA. In Group II (n = 1046), reference Cl was determined by the Brøchner-Mortensen four-sample clearance method (ClBM). The plasma time-activity curves of Group I were used to derive two mean sojourn time-based formulas (Formulas 1 and 2) for calculation of a single-sample clearance. Formula 1 was derived from the entire time-activity curve, whereas the derivation of Formula 2 used only the final slope of the time-activity curve. The accuracy of the two formulas and the Christensen and Groth 99mTc-DTPA formula was tested on Group II.

RESULTS

Chromium-51-EDTA Cl calculated by Formula 1 was almost identical to the Cl calculated by the reference Cl method (r = 0.982; SDdiff = 5.82 ml/min). Both 51Cr-EDTA Cl calculated by Formula 2 and by the 99mTc-DTPA formula showed close correlation with the reference method (r = 0.976, r = 0.985, respectively) but systematically overestimated GFR for the whole range of clearance values by 3.5 and 3.2 ml/min (p<0.001), respectively.

CONCLUSION

It is possible to get an accurate determination of 51Cr-EDTA Cl from a single-plasma sample in adults by the mean sojourn time methodology. The determination is marginally more accurate (p<0.001) if using a formula derived from the entire plasma time-activity curve than from only the final slope. The single-sample formula derived for determination of 99mTc-DTPA Cl tends slightly to overestimate GFR if used to calculate 51Cr-EDTA Cl.

Male patients with congestive heart failure and their conception of the life situation

Patients with congestive heart failure (CHF) are an extensive group in Sweden both with regard to prevalence and number of medical care events. As the age of the population and survival after myocardial infarction are increasing, the incidence of CHF is also on the rise. The aim of this study is to describe, from a nurse's perspective, how male patients with CHF conceive their life situation. Interview questions were designed with a focus on five dimensions: the biophysical, the sociocultural, the emotional, the intellectual, and the spiritual-existential. A qualitative method was used with a phenomenographic approach as it examines aspects of the surroundings as conceived. In the results, six categories emerged: feeling a belief in the future, gaining awareness, feeling support from the environment, feeling limitation, feeling a lack of energy and feeling resignation. The mental and physical lack of energy which patients feel easily leads to limited working capacity and social activities. This limitation may cause patients with CHF to believe that neither they nor their environment can influence their life situation and there is a risk that these patients become resigned. In order to help them get out of this vicious circle of limitation and resignation, it is important that the nurse teaches them self-care and shows them the possibilities that exist in everyday life. With increased awareness of their life situation, patients may adapt to their CHF and see that it is possible to improve their future themselves.

Glutathione metabolism in newborns: evidence for glutathione deficiency in plasma, bronchoalveolar lavage fluid, and lymphocytes in prematures

Respiratory distress in premature newborns is associated with deficiency of surfactant in the bronchoalveolar lining fluid; this may be influenced by a local deficiency of antioxidants. Severe L-buthionine-S,R-sulfoximine-induced depletion of glutathione (GSH, a major antioxidant) in rodents is associated with lung type 2 cell lamellar body damage and decreased concentrations in lung and bronchoalveolar lavage fluid (BALF) of phosphatidyl choline (a major component of surfactant). At birth, prematurely born newborns (30-34 weeks) had lower peripheral venous plasma GSH concentrations than term (> 36 weeks) babies; these levels decreased further with increasing prematurity (< 27 weeks, with respiratory distress). On day 2, the peripheral venous plasma GSH concentrations reached a nadir, and the lowest levels were found in the most premature newborns. Lymphocyte GSH concentrations were lowest on day 2 and day 7, and in prematures (< 27 weeks, with respiratory distress) remained below adult lymphocyte GSH levels for at least 4 weeks. At birth, prematures (< 27 weeks, with respiratory distress) had a central plasma arterio-venous (A-V) GSH gradient across the lung (an estimate of lung uptake of GSH) of 0.72 +/- 0.15 (mean +/- SD) mumol/L; on day 2, the A-V gradient did not change significantly (0.49 +/- 0.09 mumol/L). At birth, these prematures had markedly decreased BALF GSH concentrations (compared with adult levels), and they were not significantly changed during the first 4 weeks of life. These results suggest that GSH deficiency is present in prematures and that it increases with the degree of prematurity. At birth, GSH deficiency will compromise the lungs' defense against oxidative stress injury. Oxidative stress is likely to increase if hyperoxic treatment is given for respiratory distress in these infants.

The chemical nature, purity and stability of 99mTc-N-(2,6-Diethyl-3-iodo-phenylcarbamoylmethyl)-iminodiacetic acid

The chemical purity and stability of a radio pharmaceutical 99mTc-N-(2,6-diethyl-3-iodo-phenylcarbamoylmethyl)-iminodiacetic acid (IODIDA) has been studied using HPLC. The HPLC results indicate that IODIDA decomposed into at least three species after 99mTc labelling, and the amount of these varied with time. Mass spectra obtained by negative ion FABMS of no-carrier-added (NCA) Tc-labelled IODIDA showed, in addition to the molecular ion and the sodium adduct of N-(2,6-diethyl-3-iodo-phenylcarbamoylmethyl)-iminodiacetic acid, peaks corresponding to sodium containing dimers, trimers and tetramers. Several peaks were also found that may be assigned to 99Tc(I) containing dimers, trimers and tetramers.

L-2-oxothiazolidine-4-carboxylate, a cysteine precursor, stimulates growth and normalizes tissue glutathione concentrations in rats fed a sulfur amino acid-deficient diet

The efficiency of L-2-oxothiazolidine-4-carboxylate, a cysteine precursor, in stimulating glutathione synthesis and growth was evaluated in growing rats. Animals were fed a sulfur amino acid-deficient diet (0.25% L-methionine and no cysteine) supplemented with L-2-oxothiazolidine-4-carboxylate (0.35%) for 3 wk and compared with age-matched animals receiving the sulfur amino acid-deficient diet alone. Rats fed the sulfur amino acid-deficient diet had lower glutathione concentrations in bronchoalveolar lining fluid, lung, lymphocytes, and liver than rats fed a sulfur amino acid-deficient diet supplemented with L-2-oxothiazolidine-4-carboxylate. Rats fed the supplemented diet had normal tissue and bronchoalveolar lining fluid glutathione levels. Central venous plasma glutathione concentrations, mostly reflecting liver excretion, were less affected by L-2-oxothiazolidine-4-carboxylate supplementation. Rats fed L-2-oxothiazolidine-4-carboxylate supplementation had normal weight gain compared with a much lower weight gain in animals fed the sulfur amino acid-deficient diet alone. Thus, L-2-oxothiazolidine-4-carboxylate increased tissue glutathione concentrations and stimulated growth in rats. The lung glutathione status of the rats was reflected by glutathione concentrations in lymphocytes and the bronchoalveolar lining fluid, but not by the central venous plasma glutathione concentrations.