Residual radiological opacities correlate with disease outcomes in ICU-treated COVID-19

Background

Few studies consider both radiological and functional outcomes in COVID-19 survivors treated in the intensive care unit (ICU). We investigated clinical findings and pulmonary abnormalities on chest computed tomography (CT) and compared outcomes of severe versus mild-moderate acute respiratory distress syndrome (ARDS) on long-term follow-up.

Methods

This longitudinal cohort study included 118 COVID-19 patients (median age, 58 years; 79% men). Thoracic CT scans were performed 4, 10, and 22 months after hospital discharge. Two independent blinded radiologists analyzed the 10 months scans and scored the radiology findings semi-quantitatively, as no/minor versus widespread opacities [low-radiology opacity grade (ROG) versus high-ROG]. ARDS severity was based on the PaO2/FiO2 ratio. The 6 min walk test (6MWT) was performed after 3 and 9 months, and lung diffusion capacity for carbon monoxide (DLCO) and lung volume measurement after 9 and 15 months. Dynamic spirometry was done at all time points. Residual symptoms and health-related quality-of-life (HRQL) were evaluated using validated questionnaires.

Results

At 10 months, most patients (81/118; 69%) were classified as high-ROG, of which 70% had severe ARDS during hospitalisation; 69% of those with mild-moderate ARDS also had high-ROG. Patients with high-ROG had longer ICU stay and lower PaO2/FiO2 during hospitalisation (p < 0.01). At 9 months follow-up, patients with high-ROG had smaller lung volumes as % of predicted values [mean (±CI): 80 (77-84) vs. 93 (88-98) (p < 0.001)], lower DLCO as % of predicted values [74 (70-78) vs. 87 (82-92) (p < 0.001)], lower oxygen saturation during 6MWT (p = 0.02), and a tendency to more severe dyspnoea (p = 0.07), but no difference was found in HRQL compared with no/minor ROG (p = 0.92). A higher opacity score was related to lower DLCO at follow-up (r = -0.48, p < 0.001, Spearman rank test). Severe ARDS patients had slightly more severe fatigue at 9 months compared to mild-moderate, but no differences in dyspnoea or lung function at follow-up. Fibrotic-like changes were found in 93% of patients examined with CT scans at 2 years (55/118; 47%). Severe ARDS could predict widespread opacities (ROG > 25%) in most patients at follow-up at 10 months (AUC 0.74).

Conclusion

Residual radiological abnormalities in ICU-treated COVID-19 patients, evaluated for up to 2 years, relate to persisting symptoms and impaired lung function, demanding careful follow-up regardless of ARDS severity at hospitalisation.

Insights on microstructural evolution and capacity fade on diatom [Formula: see text] anodes for lithium-ion batteries

[Formula: see text] is a promising material for developing high-capacity anodes for lithium-ion batteries (LIBs). However, microstructural changes of [Formula: see text] anodes at the particle and electrode level upon prolonged cycling remains unclear. In this work, the causes leading to capacity fade on [Formula: see text] anodes were investigated and simple strategies to attenuate anode degradation were explored. Nanostructured [Formula: see text] from diatomaceous earth was integrated into anodes containing different quantities of conductive carbon in the form of either a conductive additive or a nanometric coating layer. Galvanostatic cycling was conducted for 200 cycles and distinctive trends on capacity fade were identified. A thorough analysis of the anodes at selected cycle numbers was performed using a toolset of characterization techniques, including electrochemical impedance spectroscopy, FIB-SEM cross-sectional analysis and TEM inspections. Significant fragmentation of [Formula: see text] particles surface and formation of filigree structures upon cycling are reported for the first time. Morphological changes are accompanied by an increase in impedance and a loss of electroactive surface area. Carbon-coating is found to restrict particle fracture and to increase capacity retention to 66%, compared to 47% for uncoated samples after 200 cycles. Results provide valuable insights to improve cycling stability of [Formula: see text] anodes for next-generation LIBs.

[Myositis-related interstitial lung disease - a systemic autoimmune desease often overlooked]

Interstitial lung disease can be the first sign of systemic autoimmune disease. If associated with myositis, interstitial lung disease may be the only symptom, with no presence of muscular weakness or other extramuscular manifestations. ANA-testing performed with indirect immune fluorescence may be negative. Testing for myositis antibodies should be considered as a step in the diagnostic process when strong clinical suspicion of interstitial lung disease of unknown origin is present. If interstitial lung disease is suspected, the patients should be referred to a specialist clinic for further investigation and, if possible, for discussion within a multidisciplinary team. Early suspicion of systemic inflammatory disease, rapid diagnosis and early start of treatment are crucial for future prognosis, quality of life and survival.

Novel carbon coating on aluminum current collectors for lithium-ion batteries

Abstract

In this work a significant improvement of the performance of LiFePO4 (LFP) composite cathodes, in particular at high rates (up to 12C), is demonstrated by the use of carbon-coated aluminum current collectors. The coating procedure is novel, and allows for application of a thin carbon layer without the use of solvent and binder. The presence of the thin carbon coating is verified by collecting the Raman spectra. The spectra are dominated by the D-band, indicating a low the degree of graphitization and a high amount of disordered carbon in the sample. LFP cathodes with an area capacity of 1.7 mAh/cm2 show an excellent rate capability of 89% upon cycling at 5C. A dramatic reduction of the contact resistance towards the active cathode material has been verified for the coated current collectors. It is furthermore shown that the electrochemical impedance spectra for cathodes applied on uncoated current collectors is dominated by the contact resistance, while the charge transfer resistance dominates the spectrum for cathodes applied to the carbon-coated current collector.

Article Highlights

On the Durability of Protective Titania Coatings on High-Voltage Spinel Cathodes

TiO₂ -coating of LiNi_0.5-x Mn_1.5+x O₄ (LNMO) by atomic layer deposition (ALD) has been studied as a strategy to stabilize the cathode/electrolyte interface and mitigate transition metal (TM) ion dissolution. The TiO₂ coatings were found to be uniform, with thicknesses estimated to 0.2, 0.3, and 0.6 nm for the LNMO powders exposed to 5, 10, and 20 ALD cycles, respectively. While electrochemical characterization in half-cells revealed little to no improvement in the capacity retention neither at 20 nor at 50 °C, improved capacity retention and coulombic efficiencies were demonstrated for the TiO₂ -coated LNMO in LNMO||graphite full-cells at 20 °C. This improvement in cycling stability could partly be attributed to thinner cathode electrolyte interphase on the TiO₂ -coated samples. Additionally, energy-dispersive X-ray spectroscopy revealed a thinner solid electrolyte interphase on the graphite electrode cycled against TiO₂ -coated LNMO, indicating retardation of TM dissolution by the TiO₂ -coating.

Improved electrochemical performance and solid electrolyte interphase properties of electrolytes based on lithium bis(fluorosulfonyl)imide for high content silicon anodes

Electrodes containing 60 wt% micron-sized silicon were investigated with electrolytes containing carbonate solvents and either LiPF₆ or lithium bis(fluorosulfonyl)imide (LiFSI) salt. The electrodes showed improved performance, with respect to capacity, cycling stability, rate performance, electrode resistance and cycle life with the LiFSI salt, attributed to differences in the solid electrolyte interphase (SEI). Through impedance spectroscopy, cross sectional analysis using transmission electron microscopy (TEM) and focused ion beam (FIB) in combination with scanning electron microscopy (SEM), and electrode surface characterization by X-ray photoelectron spectroscopy (XPS), differences in electrode morphological changes, SEI composition and local distribution of SEI components were investigated. The SEI formed with LiFSI has a thin, inner, primarily inorganic layer, and an outer layer dominated by organic components. This SEI appeared more homogeneous and stable, more flexible and with a lower resistivity than the SEI formed in LiPF₆ electrolyte. The SEI formed in the LiPF₆ electrolyte appears to be less passivating and less flexible, with a higher resistance, and with higher capacitance values, indicative of a higher interfacial surface area. Cycling in LiPF₆ electrolyte also resulted in incomplete lithiation of silicon particles, attributed to the inhomogeneous SEI formed. In contrast to LiFSI, where LiF was present in small grains in-between the silicon particles, clusters of LiF were observed around the carbon black for the LiPF₆ electrolyte.

Lithiation of silicon in an LiFSI electrolyte results in a bilayer SEI, with an inner, inorganic layer, and an outer, organic. This SEI is more conductive, flexible and homogeneous compared to the SEI formed in an LiPF₆ electrolyte.

Limitations of Ultrathin Al2O3 Coatings on LNMO Cathodes

This study demonstrates the application of Al₂O₃ coatings for the high-voltage cathode material LiNi_0.5-x Mn_1.5+x O_4-δ (LNMO) by atomic layer deposition. The ultrathin and uniform coatings (0.6-1.7 nm) were deposited on LNMO particles and characterized by scanning transmission electron microscopy, inductively coupled plasma mass spectrometry, and X-ray photoelectron spectroscopy. Galvanostatic charge discharge cycling in half cells revealed, in contrast to many published studies, that even coatings of a thickness of 1 nm were detrimental to the cycling performance of LNMO. The complete coverage of the LNMO particles by the Al₂O₃ coating can form a Li-ion diffusion barrier, which leads to high overpotentials and reduced reversible capacity. Several reports on Al₂O₃-coated LNMO using alternative coating methods, which would lead to a less homogeneous coating, revealed the superior electrochemical properties of the Al₂O₃-coated LNMO, suggesting that complete coverage of the particles might in fact be a disadvantage. We show that transition metal ion dissolution during prolonged cycling at 50 °C is not hindered by the coating, resulting in Ni and Mn deposits on the Li counter electrode. The Al₂O₃-coated LNMO particles showed severe signs of pitting dissolution, which may be attributed to HF attack caused by side reactions between the electrolyte and the Al₂O₃ coating, which can lead to additional HF formation. The pitting dissolution was most severe for the thickest coating (1.7 nm). The uniform coating coverage may lead to non-uniform conduction paths for Li, where the active sites are more susceptible to HF attack. Few benefits of applications of very thin, uniform, and amorphous Al₂O₃ coatings could thus be verified, and the coating is not offering long-term protection from HF attack.

Negative effects of iodine-based contrast agent on renal function in patients with moderate reduced renal function hospitalized for COVID-19

BACKGROUND

Kidney disease and renal failure are associated with hospital deaths in patients with COVID - 19. We aimed to test if contrast enhancement affects short-term renal function in hospitalized COVID - 19 patients.

METHODS

Plasma creatinine (P-creatinine) was measured on the day of computed tomography (CT) and 24 h, 48 h, and 4-10 days after CT. Contrast-enhanced (n = 142) and unenhanced (n = 24) groups were subdivided, based on estimated glomerular filtration rates (eGFR), > 60 and ≤ 60 ml/min/1.73 m2. Contrast-induced acute renal failure (CI-AKI) was defined as ≥27 μmol/L increase or a > 50% rise in P-creatinine from CT or initiation of renal replacement therapy during follow-up. Patients with renal replacement therapy were studied separately. We evaluated factors associated with a > 50% rise in P-creatinine at 48 h and at 4-10 days after contrast-enhanced CT.

RESULTS

Median P-creatinine at 24-48 h and days 4-10 post-CT in patients with eGFR> 60 and eGFR≥30-60 in contrast-enhanced and unenhanced groups did not differ from basal values. CI-AKI was observed at 48 h and at 4-10 days post contrast administration in 24 and 36% (n = 5/14) of patients with eGFR≥30-60. Corresponding figures in the eGFR> 60 contrast-enhanced CT group were 5 and 5% respectively, (p < 0.037 and p < 0.001, Pearson χ2 test). In the former group, four of the five patients died within 30 days. Odds ratio analysis showed that an eGFR≥30-60 and 30-day mortality were associated with CK-AKI both at 48 h and 4-10 days after contrast-enhanced CT.

CONCLUSION

Patients with COVID - 19 and eGFR≥30-60 had a high frequency of CK-AKI at 48 h and at 4-10 days after contrast administration, which was associated with increased 30-day mortality. For patients with eGFR≥30-60, we recommend strict indications are practiced for contrast-enhanced CT. Contrast-enhanced CT had a modest effect in patients with eGFR> 60.

Widespread Parenchymal Abnormalities and Pulmonary Embolism on Contrast-Enhanced CT Predict Disease Severity and Mortality in Hospitalized COVID-19 Patients

Purpose: Severe COVID-19 is associated with inflammation, thromboembolic disease, and high mortality. We studied factors associated with fatal outcomes in consecutive COVID-19 patients examined by computed tomography pulmonary angiogram (CTPA).

Methods: This retrospective, single-center cohort analysis included 130 PCR-positive patients hospitalized for COVID-19 [35 women and 95 men, median age 57 years (interquartile range 51–64)] with suspected pulmonary embolism based on clinical suspicion. The presence and extent of embolism and parenchymal abnormalities on CTPA were recorded. The severity of pulmonary parenchymal involvement was stratified by two experienced radiologists into two groups: lesions affecting ≤50% or >50% of the parenchyma. Patient characteristics, radiological aspects, laboratory parameters, and 60-day mortality data were collected.

Results: Pulmonary embolism was present in 26% of the patients. Most emboli were small and peripheral. Patients with widespread parenchymal abnormalities, with or without pulmonary embolism, had increased main pulmonary artery diameter (p < 0.05) and higher C-reactive protein (p < 0.01), D-dimer (p < 0.01), and troponin T (p < 0.001) and lower hemoglobin (p < 0.001). A wider main pulmonary artery diameter correlated positively with C-reactive protein (r = 0.28, p = 0.001, and n = 130) and procalcitonin. In a multivariant analysis, D-dimer >7.2 mg/L [odds ratio (±95% confidence interval) 4.1 (1.4–12.0)] and ICU stay were significantly associated with embolism (p < 0.001). The highest 60-day mortality was found in patients with widespread parenchymal abnormalities combined with pulmonary embolism (36%), followed by patients with widespread parenchymal abnormalities without pulmonary embolism (26%). In multivariate analysis, high troponin T, D-dimer, and plasma creatinine and widespread parenchymal abnormalities on CT were associated with 60-day mortality.

Conclusions: Pulmonary embolism combined with widespread parenchymal abnormalities contributed to mortality risk in COVID-19. Elevated C-reactive protein, D-dimer, troponin-T, P-creatinine, and enlarged pulmonary artery were associated with a worse outcome and may mirror a more severe systemic disease. A liberal approach to radiological investigation should be recommended at clinical deterioration, when the situation allows it. Computed tomography imaging, even without intravenous contrast to assess the severity of pulmonary infiltrates, are of value to predict outcome in COVID-19. Better radiological techniques with higher resolution could potentially improve the detection of microthromboses. This could influence anticoagulant treatment strategies, preventing clinical detoriation.

Anodes for Li-ion batteries prepared from microcrystalline silicon and enabled by binder's chemistry and pseudo-self-healing

Silicon, while suffering from major degradation issues, has been recognized as a next promising material to replace currently used graphite in the anodes of Li-ion batteries. Several pathways to mitigate the capacity fading of silicon has been proposed, including optimization of the electrode composition. Within the present work we evaluated different binder formulations to improve the long-term performance of the Li-ion batteries’ anodes based on industrial grade silicon (Si) which is typically characterized by a particle sizes ranging from 100 nm to 5.5 microns. The decrease of pH in a binder formulation was found to detrimental for the cycling performance of Si due to enhanced formation of an ester-type bonding between the carboxylic group of the binder and hydroxyl group on the Si surface as well as cross-linking. Furthermore, the present work was focused on the use of the industrial grade Si with very high loading of Si material (up to 80% by weight) to better highlight the effects of the surface chemistry of Si and its influence on the performance of Si-based anodes in Li-ion batteries. The tested system allowed to establish a pseudo self-healing effect that manifests itself through the restoration of the anode capacity by approximately 25% and initiates after approximately 20 cycles. The stabilization of the capacity is attributed to self-limiting lithiation process. Such effect is closely related to SEI formation and transport properties of an electrode prepared from silicon of industrial grade.

[Covid-19 - radiologic and histologic features]

We here describe the current knowledge about the radiologic and histologic pulmonary features of covid-19, caused by SARS-CoV-2, and present lung histology from a case with fatal disease. Initial findings on computed tomography (CT) typically include peripheral multifocal bilateral ground-glass opacities, and correspondingly microscopic alveolar edema. This is followed by peripheral consolidations with air bronchogram and perilobular pattern on CT, signs of organizing pneumonia, corresponding to loose (potentially reversible) fibrosis. The posterior parts of the lungs and the lower lobes are typically more markedly affected. In severe disease with acute respiratory distress syndrome, thickened interlobular septa and crazy paving pattern appear on CT, which corresponds to histologic diffuse alveolar damage with, depending on the stage of the disease, features such as edema, hyaline membranes, reactive epithelium, inflammation, and fibrosis.

Nanostructured diatom earth SiO2 negative electrodes with superior electrochemical performance for lithium ion batteries

Diatomaceous earth (DE) is a naturally occurring silica source constituted by fossilized remains of diatoms, a type of hard-shelled algae, which exhibits a complex hierarchically nanostructured porous silica network. In this work, we analyze the positive effects of reducing DE SiO₂ particles to the sub-micrometer level and implementing an optimized carbon coating treatment to obtain DE SiO₂ anodes with superior electrochemical performance for Li-ion batteries. Pristine DE with an average particle size of 17 μm is able to deliver a specific capacity of 575 mA h g⁻¹ after 100 cycles at a constant current of 100 mA g⁻¹, and reducing the particle size to 470 nm enhanced the reversible specific capacity to 740 mA h g⁻¹. Ball-milled DE particles were later subjected to a carbon coating treatment involving the thermal decomposition of a carbohydrate precursor at the surface of the particles. Coated ball-milled silica particles reached stable specific capacities of 840 mA h g⁻¹ after 100 cycles and displayed significantly improved rate capability, with discharge specific capacities increasing from 220 mA h g⁻¹ (uncoated ball-milled SiO₂) to 450 mA h g⁻¹ (carbon coated ball-milled SiO₂) at 2 A g⁻¹. In order to trigger SiO₂ reactivity towards lithium, all samples were subjected to an electrochemical activation procedure prior to electrochemical testing. XRD measurements on the activated electrodes revealed that the initial crystalline silica was completely converted to amorphous phases with short range ordering, therefore evidencing the effective role of the activation procedure.

Diatomaceous earth SiO₂ anodes with superior electrochemical performance are obtained by ball milling, carbon coating and electrochemical activation of SiO₂ particles.

Co(OH)2@MnO2 nanosheet arrays as hybrid binder-free electrodes for high-performance lithium-ion batteries and supercapacitors

Co(OH)₂@MnO₂ nanosheet arrays were directly grown on nickel foam via two-step electrodeposition method with subsequent heat treatment at 170 °C.

Silica from diatom frustules as anode material for Li-ion batteries

Silica derived from algae was used as anode material in Li-ion batteries, giving a capacity of more than 700 mA h g⁻¹.

Solvent-Controlled Charge Storage Mechanisms of Spinel Oxide Electrodes in Mg Organohaloaluminate Electrolytes

Considering the improved safety, reduced cost, and high volumetric energy density associated with Mg batteries, this technology has distinct advantages for large-scale energy storage compared to other existing battery technologies. However, the divalency of the Mg²⁺ cation cause sluggish magnesiation kinetics in crystalline host materials, resulting in poor performance with regards to capacity and cycling stability for intercalation based electrodes. Here, we present a Mg battery using Mn₃O₄ as the electrode material and Mg metal as the counter electrode in a Mg organohaloaluminate electrolyte. The reversible capacity when Mn₃O₄ was used as cathode reached ∼580 mAh g^-1 at a current density of 15.4 mA g^-1, whereas a reversible capacity of ∼1800 mAh g^-1 was obtained in an anode configuration. The Mn₃O₄ in a cathode configuration shows excellent cycling stability with no loss of capacity after 500 cycles at a current density of 770 mA g^-1. As an anode, Mn₃O₄ retained 86% of its initial capacity after 200 cycles. These exceptional charge storage properties and high cycling stability are attributed to highly reversible interfacial reactions involving the electrolyte solvents. Our conclusions are supported by density functional theory calculations in addition to quantitative kinetics analysis and scanning transmission electron microscopy combined with energy dispersive spectroscopy and electron energy loss spectroscopy.

Mortality and extent of coronary artery disease in 2776 patients with type 1 diabetes undergoing coronary angiography: A nationwide study

Background In a modern perspective there is limited information on mortality by affected coronary vessels assessed by coronary angiography in patients with type 1 diabetes. The aim of the present study was to characterise distribution of coronary artery disease and impact on long-term mortality in patients with type 1 diabetes undergoing coronary angiography. Design The design of this research was a nationwide population-based cohort study. Methods Individuals ( n = 2776) with type 1 diabetes undergoing coronary angiography 2001-2013 included in the Swedish National Diabetes Registry and Swedish Coronary Angiography and Angioplasty Registry were followed for mortality until 31 December 2013 (mean 7.1 years). In 79% the indication was stable or acute coronary artery disease. Coronary artery disease was categorised into normal (21%), one- (23%), two- (18%), three- (29%) and left main-vessel disease (8%). Results Mean age was 57 years and 58% were male. Mean diabetes duration was 35 years, glycated haemoglobin was 67 mmol/mol and 44% had normal or one-vessel disease. In multivariate Cox proportional analyses hazard ratio for mortality compared with normal findings was 1.09 (95% confidence interval 0.80-1.48) for one, 1.43 (1.05-1.94) for two, 1.47 (1.10-1.96) for three and 1.90 (1.35-2.68) for left main-vessel disease. Renal failure 2.29 (1.77-2.96) and previous heart failure 1.76 (1.46-2.13) were highly associated with mortality. Standard mortality ratio the first year was 5.55 (4.65-6.56) and decreased to 2.80 (2.18-3.54) after five years. Conclusions In patients with type 1 diabetes referred for coronary angiography mortality is influenced by numbers of affected coronary vessels. The overall mortality rate was higher compared with the general population. These results support early intensive prevention of coronary artery disease in this population.

Pancreatic islet blood flow during pregnancy in the rat: an increased islet mass is associated with decreased islet blood flow

Increased blood perfusion of pancreatic islets is seen during various conditions of increased demand for insulin secretion. Pregnancy confers an increased need for insulin secretion, met by increased islet mass and volume as well as a decreased threshold for glucose-induced insulin secretion. In the present study, whole pancreatic and islet blood flow were studied with a microsphere technique in Wistar rats on days 15, 18 and 20 of pregnancy and days 2 and 7 post-partum. There were no changes in total pancreatic blood flow during pregnancy and the first post-partum week. Total blood perfusion through islet tissue expressed as flow per weight of whole pancreas was higher at day 15 of pregnancy. When islet blood flow was expressed per gram of islet tissue there was a decrease at day 18 of pregnancy. This decrease of islet blood flow was concomitant to a short-lived increase of the islet mass at the end of pregnancy. We conclude that upregulation of insulin output during late pregnancy does not specifically include increased net blood perfusion through the islets. One possible reason for this might be lack of synchronization between the proliferation of endocrine cells and angiogenesis, resulting in a relative decrease in islet vascular density in the islets.

Case report: exacerbation of hemolytic anemia requiring multiple incompatible RBC transfusions

RBC transfusions in a patient with a history of autoimmune hemolytic anemia (AIHA) can represent both a laboratory and a clinical challenge. The development of high-titer low-avidity antibodies and antibodies to high-frequency antigens may further impair the ability to identify compatible donor RBCs. Not infrequently, incompatible RBCs must be used and the desire to increase oxygen carrying capacity conflicts with the desire to avoid exacerbating the autoimmune hemolytic process with RBC transfusions. A 66-year-old Caucasian female with coronary artery disease and a history of refractory AIHA had recently developed anemia and required multiple RBC transfusions. The patient had maintained adequate RBC counts with erythropoietin and prednisone therapy for the previous 16 months. With the recent worsening of her hemolytic anemia, she had developed angina that was treated with RBC transfusions in an outpatient setting. However, her angina increased as her RBC counts decreased, leading to hospital admission for further management of her hemolytic anemia and angina. She subsequently required multiple incompatible RBC transfusions despite increased prednisone therapy and did not improve until after coronary artery stent placement and high dose IVIG therapy. This case demonstrates the usefulness of early patient phenotyping in a case of accelerating hemolytic anemia to aid in donor RBC selection, the value of communicating with clinicians and the patient regarding the use of least-incompatible RBCs, and the importance of optimizing the patient's clinical condition to avoid ischemia. In addition, it demonstrates the value of repeated attempts with IVIG treatment despite previous refractoriness to this treatment.

Clinical implications of early ST-segment variability. A report from the ASSENT 2 ST-monitoring sub-study

OBJECTIVES

Evolution of the ST-segment during acute myocardial infarction has been shown to yield more information on prognosis than invasive measurements. By continuous ST-monitoring even very occasional dynamic changes can be analysed. We have recently suggested these variations to be of prognostic importance and possibly reflect individual abilities to deal with a vascular event. We wanted to confirm these findings.

METHODS

Four hundred and forty-eight patients were included in the vectorcardiographic sub-study of the second Assessment of Safety and Efficacy of a New Thrombolytic (ASSENT 2) trial. Patients underwent 24 h of ST-monitoring. ST-trend curves were blindly analysed by two independent observers.

RESULTS

ST-variability, defined as an increase of the ST-segment shift of > or = 25 microV for 2 min or more, was found to predict death, reinfarction at 30 days or urgent revascularization. By combining variability with resolution of the ST-segment elevation we could identify a high-risk group with 9.9%, and a low-risk group with only 0.8% 30-day mortality. Hypertensive patients, suggested to have an impaired secretion of endogenous t-PA, expressed significantly more ST-variability, possibly a non-invasive marker of impaired capability of dissolving and preventing thrombi.

CONCLUSION

Small variations in ST-segment shift during the first 4 h of acute myocardial infarction predict worse outcome.

Age-induced changes in pancreatic islet blood flow: evidence for an impaired regulation in diabetic GK rats

The present study aimed to compare longitudinal variations in islet blood perfusion in rats with different degrees of impairment of glucose metabolism. For this purpose, mildly diabetic Goto-Kakizaki (GK) rats, glucose intolerant F(1) hybrids of GK and Wistar (W) rats (H), and control W rats were examined at 5 wk, 12 wk, or 1 yr of age, using the microsphere technique for blood flow measurements. W rats showed progressively increasing islet blood flow (IBF) throughout the experiment. Both GK and H rats demonstrated increasing IBF between 5 and 12 wk. However, H rats showed no further increment in IBF at 1 yr, whereas GK rats displayed a pronounced decrease in IBF between 12 wk and 1 yr of age. The augmented IBF seen in older W rats may constitute an adaptation to the increasing demand for insulin secretion in aging rats. The inability to adapt to the increased demand for insulin secretion by upregulation of islet blood flow could contribute to the progressive deterioration of glucose metabolism seen in the aging GK rat.

Mercury vapour lamps interfere with the bat defence of tympanate moths (Operophtera spp.; Geometridae)

Bats often forage near streetlamps, where they catch moths in particular. At least two hypotheses may explain the apparent increase in the availability of moths to bats feeding around streetlamps: (1) the moths become concentrated near the light and therefore more profitable to exploit; and (2) the light interferes with the moths' evasive flight behaviour. We tested the second of these hypotheses by exposing flying male winter moths, Operophtera spp., to bursts of ultrasound (26 kHz, 110 dB sound pressure level) from an electronic source. The light from a 125 W mercury vapour lamp had a quantitative effect on the moths' evasive flight response at close range (within ca 4 m), inhibiting it totally in nearly half (43%, N=125) of the cases. By contrast, moths flying in the surrounding woodland and without interference from the lamp always responded to the sound. Streetlamps of the mercury vapour type (white lamps) thus interfere with the defensive behaviour of moths and presumably increase their vulnerability to echolocating bats. This may have implications for the conservation of both moths and bats. Copyright 1998 The Association for the Study of Animal Behaviour.

Prolactin regulation of islet-derived INS-1 cells: characteristics and immunocytochemical analysis of STAT5 translocation

The major changes in pancreatic islet function during pregnancy and after exposure to lactogens are an increase in beta-cell proliferation and enhanced insulin secretion. In this study we examined INS-1 cells as a potential model for further inquiry into PRL signaling in beta-cells. Proliferation of beta-cells, insulin secretion, and quantitative immunocytochemical analysis of STAT5 translocation were studied. PRL treatment of INS-1 cells resulted in a 2- to 4-fold increase in cell proliferation compared to that in the control group. In contrast, there was no effect of PRL treatment on HIT cell proliferation and only a very small effect on RIN cell proliferation. A significant effect on INS-1 cell proliferation was observed at 10 ng/ml and reached a maximum at 200 ng/ml. PRL treatment resulted in enhanced insulin secretion from INS-1 cells. There was a time-dependent increase in insulin secretion, which when corrected for cell number was 1.5-fold greater in the PRL-treated cells. The effects of PRL on cell division and insulin secretion were glucose dependent. The presence of the JAK family of tyrosine kinases and the transcription factor STAT5 in INS-1 cells was examined by immunocytochemical techniques. Although all members of the JAK family of kinases were detected, the staining intensity of JAK-2 was noticeably more intense. Initial studies of STAT5 translocation were performed using PRL-dependent Nb2 lymphoma cells, in which PRL treatment resulted in a nearly complete translocation of cytoplasmic STAT5 to the nucleus. Under control conditions there was a near-equal fluorescence intensity of STAT5 staining in the nucleus and cytoplasm of INS-1 cells. PRL treatment resulted in a time-dependent increase in STAT5 staining in the nucleus, with a corresponding decrease in the cytoplasm. The STAT5 staining intensity in the nucleus remained elevated for the duration of PRL treatment. This effect was reversible upon removal of PRL from the medium. Besides PRL, both GH and FBS induced a similar translocation of STAT5 to the nucleus. Although present in RIN cells, no detectable changes in STAT5 were observed in RIN cells after exposure to PRL, GH, or FBS. INS-1 cells should provide a good model for further inquiry into the intracellular signaling pathways used by PRL and how these events alter islet function.

Gastric inhibitory polypeptide and splanchnic blood perfusion: augmentation of the islet blood flow increase in hyperglycemic rats

The aim of the study was to investigate how the incretin candidate hormone gastric inhibitory polypeptide (GIP) affects splanchnic blood flow, especially pancreatic islet blood flow. For this purpose, male Sprague-Dawley rats were injected intravenously with either saline or GIP (5 or 15 micrograms/kg body weight) 10 min before blood flow measurements by a microsphere technique. Furthermore, 3 min before the blood flow measurements, 1 ml of either saline or 30% D-glucose was given intravenously. All glucose-injected animals were markedly hyperglycemic (> 20 mmol/liter) at the time of the blood flow measurements. Both doses of GIP potentiated basal and glucose-stimulated insulin release. In the normoglycemic rats, the lowest dose of GIP did not affect the blood perfusion to any of the investigated organs. The highest dose of GIP decreased whole pancreatic and duodenal blood flow, whereas islet blood flow was unaffected. As a result, fractional islet blood flow was increased. In the hyperglycemic rats, where the islet blood flow was increased compared with control animals, both doses of GIP further enhanced islet blood flow. No effect on pancreatic, fractional islet, or duodenal blood flow was seen after GIP administration to hyperglycemic animals. It is concluded that administration of GIP can further augment the glucose-induced stimulation of islet blood flow. This may contribute to facilitating release of insulin from the islets.

Diet-induced obesity and pancreatic islet blood flow in the rat: a preferential increase in islet blood perfusion persists after withdrawal of the diet and normalization of body weight

The aim of the present study was to evaluate the effects of diet-induced obesity on pancreatic islet blood perfusion in normal Wistar rats. Furthermore, we investigated to what extent any obesity-associated changes in islet blood flow could be reversed after reversion to a normal diet with normalization of body weight. Young adult female Wistar rats were offered a palatable mixed high-caloric diet (cafeteria diet) in addition to standard pelleted chow. Age-matched control rats received standard pelleted chow only. After 4 weeks the diet-treated rats had a body weight of approximately 15% more than that of the controls. All diet-treated rats had decreased glucose tolerance and increased serum insulin concentrations, but basal blood glucose concentrations were similar in anesthetized diet-treated and control rats. Whole pancreatic and islet blood flow rates were measured with a microsphere technique. The islet blood flow as well as fractional islet blood flow were increased (P < 0.01) in rats fed the cafeteria diet, while blood perfusion of the whole pancreas was similar to that of the control rats. In a second experiment, rats received the cafeteria diet for 4 weeks and were then fed standard pelleted food alone for another 3 weeks, while controls received standard diet for 7 weeks. After this period total body weight, retroperitoneal fat pad weight and glucose tolerance were similar to those of the controls. Whole pancreatic blood flow was unchanged as compared with that of control rats. However, both islet blood flow (P < 0.01) and fractional blood flow (P < 0.01) were increased. We conclude that diet-induced obesity in rats is associated with decreased glucose tolerance, hyperinsulinemia and a specific increase in absolute and fractional islet blood perfusion. This increase persists for at least 3 weeks after the diet is withdrawn despite normalization of body weight and glucose tolerance.

L-arginine and pancreatic islet blood flow in anesthetized rats

The aim of the present study was to see if L-arginine, which induces insulin release and is a precursor of the endothelial-derived relaxing factor nitric oxide, affects whole pancreatic and/or islet blood flow. For this purpose, anesthetized male Sprague-Dawley rats were injected intravenously with either saline or L-arginine (25, 100 or 250 mg/kg body weight). All doses of arginine caused a slight increase in blood glucose concentration, while the highest dose (250 mg/kg body weight) also increased insulin concentration. However, no changes in either mean arterial blood pressure, whole pancreatic or islet blood flow could be discerned with any of the doses of arginine used. It is concluded that insulin release is not necessarily associated with an increased islet blood perfusion.

Dynamic on-line vectorcardiography improves and simplifies in-hospital ischemia monitoring of patients with unstable angina

OBJECTIVES

This study sought to validate computerized vectorcardiography against the established technique of Holter electrocardiographic (ECG) monitoring and to compare the feasibility of the two methods for monitoring patients with unstable angina pectoris.

BACKGROUND

Detection of myocardial ischemic episodes is an important objective in patients admitted to the hospital for unstable angina pectoris. Standard ECG monitoring may be sufficient for detection of symptomatic episodes but will often overlook silent ischemia. Holter ECG monitoring has a higher likelihood of discovering such episodes, but analysis is time-consuming, and the results are not available on-line.

METHODS

We simultaneously monitored 53 consecutive patients with unstable angina, 46 of whom had technically adequate 24-h Holter ECGs and computerized vectorcardiograms.

RESULTS

The Holter tapes had a mean (+/- SD) of 15.3 +/- 10.3 h of recording with both channels technically adequate for analysis compared with 23.7 +/- 1.77 h of vectorcardiographic recording that could be analyzed (p < 0.01). Of the 15 symptomatic episodes detected by Holter ECG monitoring, 13 were also detected with dynamic vectorcardiography. In contrast, eight patients had 18 episodes of chest pain, with simultaneous ST segment changes detected by dynamic vectorcardiography; only 9 of these episodes were also detected by Holter ECG monitoring.

CONCLUSIONS

Monitoring of myocardial ischemia with dynamic vectorcardiography seems to be more efficient than Holter monitoring and may have a higher sensitivity. Computerized, continuous vectorcardiography has a complete real-time capacity, allowing monitoring over prolonged periods of time, and the results are immediately available without time-consuming analysis.

The blood flow in pancreatico-duodenal grafts in rats: inhibition of nitric oxide synthase preferentially decreases islet blood flow

In this study normoglycemic inbred Wistar-Furth rats were implanted with a syngeneic pancreatico-duodenal graft, i.e. a denervated pancreas. The blood flow to the intact native pancreas and to the transplanted gland was measured with a microsphere technique in anesthetized rats 2 weeks after transplantation. The animals were given an intravenous injection with saline alone, NG-nitro-L-arginine (25 mg/kg body weight) or sodium nitroprusside (10 micrograms/kg body weight) 10 min before blood flow measurements. Administration of NG-nitro-L-arginine increased mean arterial blood pressure and caused a pronounced decrease in whole pancreatic blood flow in both the native and transplanted gland. The islet blood flow was more markedly decreased by NG-nitro-L-arginine in both the native and transplanted pancreas, and constituted about 4% of whole pancreatic blood flow compared with 10% in the control animals. Sodium nitroprusside markedly decreased mean arterial blood pressure, but did not affect pancreatic or islet blood flow in any of the glands. It is concluded that inhibition of nitric oxide synthase causes a preferential decrease in islet blood flow both in the native pancreas and in the transplanted pancreas. This suggests that nitric oxide which affects islet blood flow is mainly endothelial-derived, and does not emanate from external nervous fibers.

Inhibition of nitric oxide synthase by NG-nitro-L-arginine causes a preferential decrease in pancreatic islet blood flow in normal rats and spontaneously diabetic GK rats

To elucidate the effect of nitric oxide (NO) on the blood flow of the pancreatic islets, the NO synthase inhibitor NG-nitro-L-arginine (N-arg; 25 mg/kg BW) was administered iv to rats 10 min before pancreatic blood flow was measured with a nonradioactive microsphere technique. In male Sprague-Dawley rats, N-arg induced a marked decrease in islet blood flow (16 +/- 4 vs. 44 +/- 8 microliters/min.g pancreas; P < 0.001) and a less pronounced decrease in whole pancreatic blood flow (0.27 +/- 0.04 vs. 0.43 +/- 0.06 ml/min.g; P < 0.05), leading to a markedly decreased fractional islet blood flow (5.5 +/- 0.9% vs. 10.3 +/- 1.3%; P < 0.02). In a second experiment, injection of D-glucose (300 mg/kg BW, iv) in male Sprague-Dawley rats induced a selective increase in islet blood flow (P < 0.05). Such an increase has previously been shown to be mediated by a vagal cholinergic mechanism. Administration of N-arg to these rats resulted in decreased pancreatic (P < 0.05), islet (P < 0.001), and fractional (P < 0.001) islet blood flow, which did not differ from those observed in normoglycemic rats after treatment with N-arg. Furthermore, we studied the mechanism behind the previously described increase in islet blood perfusion, mediated by the vagus nerve, in F1-hybrids of the GK (Goto-Kakizaki) rat, a spontaneous animal model of noninsulin-dependent diabetes mellitus. Administration of N-arg to female GK rats resulted in decreases in islet (P < 0.001), pancreatic (P < 0.01), and fractional islet blood flow (P < 0.001) to the levels observed in female Wistar rats treated in parallel. These data are consistent with the possibility that NO is an important physiological regulator of islet blood flow. Furthermore, the vagally dependent high levels of islet blood flow demonstrated in the GK rat appear to be mediated by a mechanism involving NO.

Pancreatic and islet blood flow in F1-hybrids of the non-insulin-dependent diabetic GK-Wistar rat

Previous studies have indicated that various conditions under which an increased functional load is posed on the pancreatic islets, e.g. partial pancreatectomy and continuous glucose infusions, may influence the microcirculation of the pancreas. To investigate further the effects of elevated functional demand on the islets, the blood perfusion of the whole pancreas and the pancreatic islets was measured with a microsphere technique in an animal model presenting impaired glucose tolerance and mild hyperglycemia, namely F1-hybrids of the spontaneously non-insulin-dependent diabetic GK-Wistar rat. Normal Wistar rats served as controls. All hybrids had a pathological intraperitoneal glucose tolerance test 1 week before the blood flow measurements, which were performed in 10-12-week-old rats. Both the whole pancreatic and the islet blood flows were increased in the hybrids compared to controls. The fractional islet blood flow, i.e. the fraction of whole pancreatic blood flow diverted through the islets, also was increased in the hybrid rats (12.6 +/- 0.6% vs 9.8 +/- 0.5% in controls, p < 0.01). A bilateral abdominal vagotomy performed 30 min before the blood flow measurement markedly decreased the blood flow values of the islets and the whole pancreas in both groups of rats. After vagotomy, the islet blood flow in the hybrid rats was similar to that of the vagotomized control animals (8.2 +/- 0.8 and 7.5 +/- 1.4%, respectively). It is concluded that the increased pancreatic and islet blood perfusion observed in F1-hybrids of the GK-Wistar rat depends on a mechanism mediated by the vagus nerve.

Pancreatic islet blood flow in the rat after administration of islet amyloid polypeptide or calcitonin gene-related peptide

Anesthetized male Sprague-Dawley rats (350-400 g) were injected intravenously with either 0.1, 1, 15, or 25 nmol rat islet amyloid polypeptide (IAPP), 65 or 650 pmol rat calcitonin gene-related peptide (CGRP), or saline alone. IAPP at the two highest doses decreased the mean arterial blood pressure (BP), increased blood glucose concentrations, and decreased serum insulin concentrations. CGRP at both doses decreased the BP but did not affect the blood glucose concentrations. The blood flow to the whole pancreas, pancreatic islets, adrenal glands, colon, duodenum, liver, and kidney was measured with a microsphere technique 30 min after administration of IAPP and 3 min after injection of CGRP. The two higher doses of IAPP (15 and 25 nmol) markedly reduced the whole pancreatic blood flow, whereas the islet blood flow remained unaffected. This resulted in an increase in the fraction of whole pancreatic blood flow diverted through the islets from approximately 10 to 17%. No blood flow changes in the pancreas or the islets were observed when 0.1 or 1 nmol IAPP was injected. CGRP at both doses caused a decrease in both whole pancreatic and islet blood flow. No changes in fractional islet blood flow were observed, despite similar effects on mean arterial BP as observed after IAPP injections. Neither adrenal, duodenal, colonic, hepatic, skeletal muscle, nor renal blood flow were significantly affected by any of the concentrations of IAPP used, whereas 650 pmol CGRP decreased both duodenal and colonic blood flow. We conclude that IAPP and CGRP have different effects on pancreatic islet blood flow and that IAPP may be of importance for islet blood flow regulation.

Early electrocardiographic changes in acute myocardial infarction treated by streptokinase or alteplase: a randomized study with dynamic, multi-lead, electrocardiographic monitoring

Patients with a patent coronary artery after reperfusion therapy show an increased rate of evolution of QRS changes and of resolution of S-T changes as compared to patients with a persistent occlusion. Dynamic vectorcardiography permits multi-lead monitoring of changes in QRS complex and S-T segment over time. We monitored 150 patients randomized to alteplase or streptokinase for 24 h after admission. Alteplase was associated with significantly more rapid evolution of electrocardiographic changes but also with an increased occurrence of recurrent S-T changes. This may indicate a higher rate of early reperfusion with alteplase but due to recurrent ischemia, an electrocardiographic catch-up is seen with similar extent of myocardial damage observed after 24 h of monitoring.

Glucose metabolism in embryos of normal and diabetic rats during organogenesis

To investigate whether malformations in the offspring of diabetic rats are related to a disturbed embryonic glucose metabolism, lactate production, lactate content and glucose oxidation in embryos of normal and manifestly diabetic rats were measured in vitro during the period of organogenesis. The embryonic production and content of lactate decreased by 90% between gestational days 10 and 11. On both gestational days the embryos of diabetic rats showed increased lactate production and content compared to the embryos of normal rats. The embryonic oxidation of glucose decreased slightly from gestational day 10 to day 11, and the embryos of diabetic rats exhibited a lower glucose oxidation rate than those of normal rats on both days. The lactate production and content in the embryos increased with increasing concentrations of glucose in the incubation medium, whereas the oxidation of glucose was unaffected by the glucose concentration. The results suggest that the embryonic metabolism of glucose is only marginally affected by changes in the availability of glucose. The lactate production rate was higher and the glucose oxidation rate lower in the embryos of diabetic than in those of normal rats, even when the values for these metabolic variables were normalized to the embryonic DNA content. Thus, a causative role for a disturbance of the glucose metabolism in diabetes-induced embryonic dysmorphogenesis could be envisaged.

The volume and area of the capillaries in the endocrine and exocrine pancreas of the rat

The capillary volumes in the endocrine and exocrine parenchyma of the pancreas were compared with a point-sampling technique. The islets were found to have a capillary volume of approximately 3.5%, while the value for the exocrine pancreas was significantly (P less than 0.001) lower at 2%. When the capillary wall area was measured, however, both types of parenchyma had a similar value of approximately 20 mm2/mm3 tissue. The reason for the discrepancy between these parameters is probably the lack of lymphatic capillaries, with their relatively small lumen in the islets.