Influence of meteorological variables and air pollutants on measurements from automatic pollen sampling devices

This study examines the influence of meteorological factors and air pollutants on the performance of automatic pollen monitoring devices, as part of the EUMETNET Autopollen COST ADOPT-intercomparison campaign held in Munich, Germany, during the 2021 pollen season. The campaign offered a unique opportunity to compare all automatic monitors available at the time, a Plair Rapid-E, a Hund-Wetzlar BAA500, an OPC Alphasense, a KH-3000 Yamatronics, three Swisens Polenos, a PollenSense APS, a FLIR IBAC2, a DMT WIBS-5, an Aerotape Sextant, to the average of four manual Hirst traps, under the same environmental conditions. The investigation aimed to elucidate how meteorological factors and air pollution impact particle capture and identification efficiency. The analysis showed coherent results for most devices regarding the correlation between environmental conditions and pollen concentrations. This reflects on one hand, a significant correlation between weather and airborne pollen concentration, and on the other hand the capability of devices to provide meaningful data under the conditions under which measurements were taken. However, correlation strength varied among devices, reflecting differences in design, algorithms, or sensors used. Additionally, it was observed that different algorithms applied to the same dataset resulted in different concentration outputs, highlighting the role of algorithm design in these systems (monitor + algorithm). Notably, no significant influence from air pollutants on the pollen concentrations was observed, suggesting that any potential difference in effect on the systems might require higher air pollution concentrations or more complex interactions. However, results from some monitors were affected to a minor degree by specific weather variables. Our findings suggest that the application of real-time devices in urban environments should focus on the associated algorithm that classifies pollen taxa. The impact of air pollution, although not to be excluded, is of secondary concern as long as the pollution levels are similar to a large European city like Munich.

Angiography derived index of microvascular resistance (IMR) in Takotsubo syndrome

Background and purpose

Coronary microvascular dysfunction (CMD) has been proposed as a key driver in the etiopathogenesis of Takotsubo syndrome (TTS), likely related to an “adrenergic storm” upon a susceptible microvascular circulation. The aim of our manuscript was to assess and quantify CMD in patients with TTS through angiography-derived index of microcirculation (IMR) and evaluate its correlation with clinical presentation.

Methods

Coronary angiograms of 41 consecutive TTS patients were retrospectively offline analyzed to derive angiography-based indices of CMD. Three recently developed indices (NH-IMRangio, AngioIMR and A-IMR) were calculated and compared based on Quantitative Flow Reserve (QFR) analysis. CMD was defined as an IMRangio ≥25 units. The correlation between CMD and clinical presentation and outcomes was then assessed.

Results

Median age was 76 years, 85.7% were women and mean left ventricular ejection fraction (LVEF) at first echocardiogram was 41.2%. Angiography-derived IMR was higher in Left Anterior Descending artery (LAD) than Circumflex artery (LCX) and Right Coronary artery (RCA) with either NH-IMRangio (52.7 vs 35.3 vs 41.4), AngioIMR (47.2 vs 31.8 vs 37.3) or A-IMR (52.7 vs 36.1 vs 41.8). All patients presented CMD with angiography-derived IMR ≥25 in at least one territory with each formula. Angiography-derived IMR in LAD territory was significantly higher in patients presenting with LVEF impairment (≤40%) than in those with preserved ventricular global function (NH-IMRangio: 59.3 vs 46.3, p. value=0.030; AngioIMR: 52.9 vs 41.4, p-value=0.037; A-IMR: 59.2 vs 46.3, p-value=0.035).

Conclusion

CMD, assessed with angiography-derived IMR, is a common finding in TTS and it is inversely correlated with LV function. The available formulas have a substantial superimposable diagnostic performance in assessing coronary microvascular function.

Funding Acknowledgement

Type of funding sources: None.

Spontaneous, independent, single-center renal denervation registry of a resistant hypertension multidisciplinary team

Background

Uncontrolled resistant hypertension (URH) is defined as PAS ≥140mmHg despite the adherence to at least 3 maximally tolerated doses of antihypertensive medications. In the adult population URH is a common condition with a prevalence that ranges between 10–15% and is related with poor prognosis and higher risk of major adverse cardiovascular events.

Renal sympathetic denervation (RDN) has recently proved efficacy in different hypertensive subsets of patients. However, patients with chronic kidney disease (CKD) IIIB-V stages (i.e. glomerular filtrate rate <45 ml/min) have been systematically excluded from randomized clinical trials (RCT).

Purpose

To evaluate the safety and the efficacy of RDN in a daily practice population of patients with URH on top of medical therapy, including patients with renal function impairment (GFR<45ml/min).

Methods

Consecutive unselected patients with URH undergoing RDN were enrolled. Indication of RDN was assessed in a multidisciplinary team involving cardiologist, nephrologist and hypertension specialists, after secondary forms of hypertension had been excluded. Efficacy was defined as the inter-individual change of office (OBP) and ambulatory blood pressure monitoring (ABPM) at 3, 6 and 12 months after RDN. Safety as the absence of any device-related major complication (BARC classification), end-stage renal disease, stroke, acute myocardial infarction and any cause of death within 1 month of the procedure. Safety and efficacy profile was assessed in patients with an estimated GFR below 45 ml/min/1.73 m2.

Results

Seventy-two patients underwent RDN for URH from 2012 to 2022. The population presented with multiple comorbidities and target organ damage: almost 50% were smoker, 43% diabetic, 33% PAD, 25% CAD and 60% CKD. Isolated systolic hypertension prevalence was 53%. The average number of antihypertensive medications at baseline was 5.3±1.1. Baseline OBP and ABPM were 158.8/86.6±23.4/15.3 mmHg and 151.4/87.6±18.8/14.2 mmHg, respectively. The vast majority of the procedures were performed with tetrapolar radio-frequency catheter (91.7%), with 37.3±14.3 number of ablations per procedure. The average amount of contrast medium was 72.1±38.1 ml. At 12-month follow-up a significant reduction of office and ambulatory systolic BP, respectively by −15.66±29.73 mmHg (P<0.01) and by −11.3±23.1mmHg (P<0.05), was noticed. BP reduction at 12-month follow-up among patients with eGFR <45 ml/min was similar to that obtained in patients with higher eGFR. No major complications were observed and renal function was stable up to 12 months, even in patients with lowest eGFR at baseline.

Conclusion(s)

RDN is safe and feasible in patients with URH on top of medical therapy, even in a high-risk CKD population with multiple comorbidities. Our experience underlines the central role of multidisciplinary team evaluation for the targeted management of uncontrolled resistant hypertension.

Funding Acknowledgement

Type of funding sources: None.

P73 ANGIOGRAPHY–DERIVED INDEX OF MICROVASCULAR RESISTANCE (IMR–ANGIO) IN TAKOTSUBO SYNDROME

Introduction

Coronary microvascular dysfunction (CMD) has been proposed as a key driver in the etiopathogenesis of Takotsubo syndrome (TTS), likely related to an “adrenergic storm” upon a susceptible microvascular circulation. The aim of our manuscript was to assess and quantify CMD in patients with TTS through non–invasive angio–derived index of microcirculation (IMRangio) and evaluate its correlation with clinical and instrumental presentation.

Methods

41 consecutive TTS patients were retrospectively analyzed. Three different formulas for compute Non–Hyperemic IMRangio (NH–IMRangio) derived by 3D–Quantitative Coronary Angiography (3D–QCA) and Quantitative Flow Reserve (QFR) analysis were used according to each fluidodynamic mathematical expression as reported by respective authors. CMD was defined as an IMRangio ≥ 25. The correlation between NH–IMRangio and clinical presentation and the comparation between the three formulas were provided.

Results

Median age was 76 years, 85.7% were women and mean left ventricular ejection fraction (LVEF) at first echocardiogram was 41.2%. NH–IMRangio was higher in Left Anterior Descending artery (LAD) than Circumflex artery (CX) and Right Coronary artery (RCA) with either NH–IMRangio 1 (52.7 vs 35.3 vs 41.4), NH–IMRangio 2 (47.2 vs 31.8 vs 37.3) or NH–IMRangio 3 (52.7 vs 36.1 vs 41.8). All patients presented CMD with NH–IMR angio ≥ 25 in at least one territory with each formula. NH–IMRangio in LAD territory was significantly higher in patients presenting with LVEF impairment (≤40%) than in those with preserved ventricular global function (NH–IMRangio LAD 1: 59.3 vs 46.3, p. value=0.030; NH–IMRangio LAD 2: 52.9 vs 41.4, p–value=0.037; NH–IMRangio LAD 3: 59.2 vs 46.3, p–value=0–035). Association between NH–IMRangio computed in LAD and LVEF showed a moderate correlation (NH–IMRangio 1: r = –0,3485, Rho = 0,1214, p = 0,0256; NH–IMRangio 2: r = –0,3513; Rho = 0,1234, p = 0,0256; NH–IMRangio 3: r = –0,3326, Rho = 0,1106, p = 0,0336). Finally, Bland–Altman plot analysis showed good agreement between NH–IMRangio 1 and 3, while NH–IMRangio 2 showed a consistent bias of –5 units against both NH–IMRangio 1 and NH–IMRangio 2 with increasing difference at higher absolute values.

Conclusion

CMD, assessed with NH–IMRangio, is a common finding in TTS and it is inversely correlate with LVEF dysfunction. The available formulas for NH–IMRangio computation have a substantial superimposable diagnostic performance in assessing CMD.

P428 PRESCRIPTION APPROPRIATENESS AND EFFECTIVE CLINICAL IMPACT OF EXERCISE STRESS TEST IN ROUTINE DAILY PRACTICE

Rationale

In the clinical setting, and particularly in the cardiovascular field, an exponential increase of non–invasive diagnostic tests has been observed. Between these, the exercise stress test represents a low–sensitivity and low–specificity diagnostic approach and its use has been less and less recommended in national and international guidelines. However, in the Italian clinical common practice it continues to be extensively prescribed both for chronic coronary syndrome (CCS) follow–up and for screening of coronary artery disease (CAD) in asymptomatic patients with multiple cardiovascular risk factors.

Materials and Methods

A retrospective cohort single–center study was conducted and 968 consecutives patients undergoing ECG stress test at our Department between October 2018 and March 2019 were included. Appropriateness of prescription and impact on the following diagnostic and therapeutic pathway has been analyzed.

Results

In this series, the main indication for exercise stress test was subclinical ischemia detection in CCS follow–up (312 pts, 32.3%). 181 tests (18.2%) were undertaken for CAD detection in patients symptomatic for chest pain and 171 (17.7%) for CAD detection in asymptomatic patients with multiple cardiovascular risk factors. At last, 97 tests (10%) were prescribed for arrhythmic burden evaluation and exercise response in patients with documented hyperkinetic arrhythmias. 590 tests (61%) were considered significative for reaching heart rate significance threshold (85% of target heart rate); between these 53 (9%) were positives for symptoms or ECG modifications. Among the positive tests, 25 patients (2.6%) went to the catheterization laboratory for coronary angiography: the indications for the exercise stress testing were chest pain for 14 of these patients while 7 undertook the examination for CCS follow–up. No asymptomatic patient presented for CAD screening undertook coronary angiography. At the end of the diagnostic pathway, 9 patients (0.9% of the complete cohort) received percutaneous or surgical revascularization.

Conclusions

Routinary and extensive use of exercise stress test can lead to dispersion of resources with many inappropriate examinations. Accurate clinical evaluation and appropriate prescription, especially regarding chest pain evaluation, are the foundations for a significative impact on clinical history of patients.

[ToSkORL: self- and objective assessment of examination skills in the head and neck region]

Hintergrund

Ein zentrales Ziel des Medizinstudiums ist der Erwerb theoretischer und praktischer Kompetenzen. Es mangelt jedoch an Evidenz, wie der Erwerb von Kompetenzen in speziellen Untersuchungstechniken gemessen werden kann. ToSkORL (Teaching of Skills in Otorhinolaryngology) ist ein Projekt, das die studentische Selbstwahrnehmung ihrer Kompetenz bei speziellen Untersuchungstechniken der Hals-Nasen-Ohren-Heilkunde und des Kopf-Hals-Bereichs aus didaktisch-wissenschaftlicher Sichtweise beleuchtet.

Methodik

Im Rahmen des Untersuchungskurses erfolgte eine standardisierte mündlich-praktische Prüfung zu neun verschiedenen Untersuchungstechniken. Vor der Prüfung erfolgte eine Evaluation der studentischen Selbsteinschätzung mittels Fragebogen, die Prüfung wurde mittels Checkliste durch die Prüfenden standardisiert geprüft. Selbst- und Fremdeinschätzung nach der Likert-Skala wurden korreliert. Die neun Untersuchungstechniken wurden jeweils 42-mal von insgesamt 91 Studierenden in gegenseitiger Untersuchung durchgeführt.

Ergebnisse

Die Selbsteinschätzung der Kompetenz in den Untersuchungstechniken variiert erheblich, insgesamt schätzten Studierende ihre eigene Untersuchungskompetenz weitgehend unabhängig von Alter und Geschlecht meist realistisch ein. Studierende mit einem hohen Interesse an der Hals-Nasen-Ohren-Heilkunde gaben bessere Selbsteinschätzungen an, neigten jedoch auch eher zur Selbstüberschätzung. Bei Untersuchungen des mittleren Schwierigkeitsniveaus ergab sich die größte Divergenz von Selbst- und Fremdeinschätzung.

Schlussfolgerung

Die studentische Selbsteinschätzung ist ein geeignetes Instrument zur Messung der Untersuchungskompetenz in der Hals-Nasen-Ohren-Heilkunde. Es sollte ein besonderer Fokus auf die Lehre vermeintlich mittelschwerer Untersuchungstechniken gelegt werden, da diese am stärksten über- und unterschätzt werden.

Zusatzmaterial online

Die Online-Version dieses Beitrags (10.1007/s00106-021-01097-y) enthält zwei Mini-Clinical-Exam(CEX)-Evaluationsbögen für Studenten und Untersucher. Beitrag und Zusatzmaterial stehen Ihnen auf www.springermedizin.de zur Verfügung. Bitte scannen Sie den QR-Code, das Zusatzmaterial finden Sie beim Beitrag unter „Ergänzende Inhalte“.

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High-resolution spatiotemporal pHe and pO2 imaging in head and neck and oesophageal carcinoma cells

Background

pO₂ and pH are physiological parameters relevant for different processes in health and disease, including wound healing and cancer progression. Head and neck squamous cell carcinomas (HNSCC) and oesophageal squamous cell carcinomas (ESCC) have a high rate of local recurrence that is partly related to treatment-resistant residual tumour cells. Hence, novel diagnostic tools are required to visualise potential residual tumour cells and thereby improve treatment outcome for HNSCC and ESCC patients. We developed a device to spatiotemporally measure oxygen consumption rates (OCR) and extracellular acidification rates (ECAR) to distinguish HNSCC and ESCC cells from healthy cells in vitro, exploiting general metabolic differences between cancer cells and healthy cells.

Methods

OCR and ECAR were measured via a newly developed device named STO₂p-Q (SpatioTemporal O₂ and pH Quantification) using the VisiSens technology based on ratiometric fluorescence imaging, facilitating spatiotemporal resolution. Results were confirmed using extracellular flux analyses (Seahorse technology).

Results

STO₂p-Q is described and used to measure OCR and ECAR in HNSCC and ESCC cell lines and normal fibroblast and epithelial cells as components of the tumour microenvironment. OCR measurements showed differences amongst HNSCC and ESCC cell lines and between HNSCC/ESCC and normal cells, which on average had lower OCR than HNSCC/ESCC cells. Both OCR and ECAR measurements were independently verified using the Seahorse technology. Additionally, using STO₂p-Q, HNSCC/ESCC, and normal cells could be spatially resolved with a resolution in the low millimetre range.

Conclusions

We developed a method to spatiotemporally measure OCR and ECAR of cells, which has many potential in vitro applications and lays the foundation for the development of novel diagnostic tools for the detection of cancerous tissue in HNSCC and ESCC patients in vivo.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40170-021-00257-6.

Higher probability of compound flooding from precipitation and storm surge in Europe under anthropogenic climate change

In low-lying coastal areas, the co-occurrence of high sea level and precipitation resulting in large runoff may cause compound flooding (CF). When the two hazards interact, the resulting impact can be worse than when they occur individually. Both storm surges and heavy precipitation, as well as their interplay, are likely to change in response to global warming. Despite the CF relevance, a comprehensive hazard assessment beyond individual locations is missing, and no studies have examined CF in the future. Analyzing co-occurring high sea level and heavy precipitation in Europe, we show that the Mediterranean coasts are experiencing the highest CF probability in the present. However, future climate projections show emerging high CF probability along parts of the northern European coast. In several European regions, CF should be considered as a potential hazard aggravating the risk caused by mean sea level rise in the future.

Higher probability of compound flooding from precipitation and storm surge in Europe under anthropogenic climate change

In low-lying coastal areas, the co-occurrence of high sea level and precipitation resulting in large runoff may cause compound flooding (CF). When the two hazards interact, the resulting impact can be worse than when they occur individually. Both storm surges and heavy precipitation, as well as their interplay, are likely to change in response to global warming. Despite the CF relevance, a comprehensive hazard assessment beyond individual locations is missing, and no studies have examined CF in the future. Analyzing co-occurring high sea level and heavy precipitation in Europe, we show that the Mediterranean coasts are experiencing the highest CF probability in the present. However, future climate projections show emerging high CF probability along parts of the northern European coast. In several European regions, CF should be considered as a potential hazard aggravating the risk caused by mean sea level rise in the future.

Comparison of folding rates of homologous prokaryotic and eukaryotic proteins

The rate of polypeptide chain elongation is up to one order of magnitude faster in prokaryotic cells than in eukaryotes. Here we report that the rates of in vitro refolding of orthologous prokaryotic and eukaryotic proteins correlate with their differential rates of biosynthesis. The mitochondrial and cytosolic aspartate aminotransferases of chicken and aspartate aminotransferase of Escherichia coli show pairwise sequence identities of 41-48% and nearly identical three-dimensional structures. Nevertheless, the prokaryotic enzyme refolded 6 times faster (at 25 degrees C) than the eukaryotic isoenzymes after denaturation in 6 m guanidine hydrochloride. Prokaryotic malate dehydrogenase and lactate dehydrogenase also renatured faster than their orthologous eukaryotic counterparts, suggesting that evolutionary pressure has adapted the rate of folding to the rate of elongation of polypeptide chains.

[Crisis and decline of bath houses]

For centuries bath-houses and barber-surgeons formed such an integral part of public life that one is mystified by their vanishing from modern view with hardly any trace left. Previous authors have offered a variety of reasons for this disappearance: the bath-houses' notorious reputation, developing fuel-shortage, the "new" fashion of taking the waters and the outbreak of previously unknown contagious diseases are among those mentioned most frequently. While these factors may be valid reasons for a crisis afflicting the "hot-houses" they would hardly explain why fate overtook the barber-surgeons' entire trade. Judging from the sources available one cannot help but feel that the philosophers of the Enlightenment were largely responsible for such a dramatic change of society. Sceptical philosophy discarded the wisdom of the ancient medical authorities replacing traditional steam-bathing with "modern" cold-bathing. Society itself was subject to equally revolutionary changes: the local masters of the trade had to make room for surgeons educated at medical schools setting the stage for a new reality which has become "normal" to us.

Secondary structure of bacteriorhodopsin fragments. External sequence constraints specify the conformation of transmembrane helices

The secondary structure of bacteriorhodopsin polypeptides comprising two (AB, CD, DE, FG), three (AC, CE, EG), four (AD, DG), or five (AE, CG) of the seven transmembrane segments has been analyzed by circular dichroism spectroscopy. A comparison of the alpha-helix content with that predicted from the high resolution structure of the native protein revealed that the N-terminal AB, AC, AD, and AE fragments and the C-terminal CG fragment are completely refolded in the presence of mixed phospholipid micelles. In contrast, the DG, EG, FG, CD, CE, and DE fragments did not form alpha-helices of the expected lengths at pH 6. Each of the latter fragments displayed, however, an increased helicity upon lowering the pH to 4. Fluorescence measurements with the CD and FG fragments suggest that this helix formation occurs within transmembrane segments C and G, respectively, and thus is likely to originate from the protonation of carboxyl residues that participate in proton translocation. The partial misfolding at neutral pH observed for the shorter fragments from the central and C-terminal part of bacteriorhodopsin indicates that the conformation of some transmembrane segments is specified by interactions with neighboring helices in the assembled structure. Moreover, the data demonstrate that two stable helices at the N terminus of a multihelical membrane protein are sufficient as a folding template to induce a native conformation to the following transmembrane domains.

Neuroprotection against oxidative stress by estrogens: structure-activity relationship

Oxidative stress-induced neuronal cell death has been implicated in different neurological disorders and neurodegenerative diseases; one such ailment is Alzheimer's disease. Using the Alzheimer's disease-associated amyloid beta protein, glutamate, hydrogen peroxide, and buthionine sulfoximine, we investigated the neuroprotective potential of estrogen against oxidative stress-induced cell death. We show that 17-beta-estradiol, its nonestrogenic stereoisomer, 17-alpha-estradiol, and some estradiol derivatives can prevent intracellular peroxide accumulation and, ultimately, the degeneration of primary neurons, clonal hippocampal cells, and cells in organotypic hippocampal slices. The neuroprotective antioxidant activity of estrogens is dependent on the presence of the hydroxyl group in the C3 position on the A ring of the steroid molecule but is independent of an activation of estrogen receptors.

Glucocorticoids enhance oxidative stress-induced cell death in hippocampal neurons in vitro

In patients with Alzheimer's disease, hippocampal cells are among the first neuronal cells of the brain to degenerate. Both rat primary hippocampal neurons and cells of the clonal mouse hippocampal cell line HT22 express endogenous functional glucocorticoid receptors (GRs), as shown by transient transfection of cells with a luciferase reporter plasmid containing GR-responsive elements. The influence of activated GRs on oxidative stress-induced neuronal cell death in vitro was investigated employing these hippocampal model systems. Two oxidative stressors were investigated, the free radical-inducing Alzheimer's disease-associated amyloid beta-protein, which is toxic to hippocampal neurons, and the excitatory amino acid glutamate, which induces oxidative cell death in HT22 cells via an increase in intracellular peroxides. Cellular viability was assessed with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide test and trypan exclusion staining, followed by microscopical cell counting. Glucocorticoids strongly increased the vulnerability of the hippocampal cells to amyloid beta-protein and glutamate. This increase could be blocked by the specific GR antagonist RU486. Our data suggest that changes in hippocampal GR homeostasis and regulation may render hippocampal neurons more vulnerable to oxidative stress-induced neuronal degeneration.

Melatonin prevents oxidative stress-induced cell death in hippocampal cells

The pineal hormone melatonin has been suggested to be a very effective antioxidant in the brain. Oxidative stress may play a role in certain neuropathological conditions and the hippocampus is an early target of neurodegeneration. Using cells of the clonal hippocampal cell line HT22 and organotypic hippocampal rat brain slice cultures, we investigated a possible protective role of melatonin against oxidative stress-induced hippocampal cell death. Glutamate alone induced oxidative apoptotic cell death in HT22 cells as detected with Hoechst staining and DNA fragmentation analysis. Preincubation with 1 mM melatonin protected HT22 cells against glutamate-induced cell death and protected organotypic hippocampal slices against H2O2-induced cell death. These findings suggest that this neurohormone may be useful in the prevention of neurodegenerative diseases.

Oxidative stress-resistant cells are protected against haloperidol toxicity

The neuroleptic drug haloperidol is cytotoxic to cells of different origin in high doses. The mechanism of haloperidol toxicity may involve oxidative stress resulting in necrosis. In the present study, we show that rat pheochromocytoma PC12 cell clones which were selected for resistance to the toxicity of the oxidative stressor amyloid beta-protein (A beta), were also resistant to haloperidol toxicity. This data strongly supports the causative involvement of free radicals in haloperidol-induced cell death.

Differential effects of molecular chaperones on refolding of homologous proteins

Three homologous aspartate aminotransferases with virtually identical spatial structures and pairwise amino acid sequence identities of > 40% differ markedly with respect to the yield of renaturation upon dilution from 6 M guanidine hydrochloride (mitochondrial << cytosolic < Escherichia coli). The enzymes also respond differently to molecular chaperones. GroEL/GroES, the Hsp60 homolog of E. coli, increased considerably the yield of renaturation of mitochondrial aspartate aminotransferase and to a lesser extent that of its cytosolic counterpart, but not that of the E. coli enzyme. DnaK/DnaJ/GrpE, the Hsp70 system of E. coli, also increased the yield of renaturation of mitochondrial aspartate aminotransferase. Apparently, specific features in the amino acid sequence or the folding pathway which are independent of the final secondary and tertiary structure determine the interactions of the folding proteins with the chaperone systems.

17-beta estradiol protects neurons from oxidative stress-induced cell death in vitro

The potential antioxidant activity of 17-beta estradiol and other steroid hormones in neuronal cells was investigated by studying oxidative stress-induced cell death caused by the neurotoxins amyloid beta protein, hydrogen peroxide and glutamate in the clonal mouse hippocampal cell line HT22. Preincubation of the cells with 10(-5) M 17-beta estradiol prior to addition of the neurotoxins prevented oxidative stress-induced cell damage and ultimately cell death, as detected with cell viability (MTT) and cell lysis (trypan blue exclusion/cell counting; propidium iodide staining) assays. At the DNA level, 17-beta estradiol blocked the DNA degradation caused by glutamate. Other steroid hormones, such as progesterone, aldosterone, corticosterone and the steroid precursor cholesterol, did not protect the cells. The neuronal protection afforded by 17-beta estradiol was estrogen receptor-independent. These data demonstrate a potent neuroprotective activity of the antioxidant 17-beta estradiol, which may have implications for the prevention and treatment of Alzheimer's disease.

[Inadvertant suture fixation of a Swan-Ganz catheter to the pulmonary artery following heart surgery]

We report a patient undergoing redo cardiac surgery for combined replacement of the aortic and mitral valves. During the course of the operation, a Swan-Ganz catheter - positioned preoperatively - was accidentally fixed to the wall of the pulmonary artery. As this did not interfere with cardiac output measurement or the pulmonary artery pressure wave form, the fixation was not noticed until an attempt was made to remove the catheter. Fluoroscopy revealed both the catheter's immobility and the location of the suture fixation. The patient required a sternotomy to remove the catheter. In order to avoid this complication, the indications for pulmonary artery catheters during cardiac surgery should be carefully considered. If catheters are inserted, their mobility should by all means be ensured before the chest is closed.

The DNA-binding properties of an artificial 42-residue polypeptide derived from a natural repressor

Bacteriophage 434 repressor recognizes the operator sequences ACAAG and ACAAT. As the same or similar sequences occur in the enhancer region of HIV-1, 434 repressor was a potential HIV enhancer-binding protein. We found that the interaction of the DNA-binding domain of 434 repressor with a 57-bp HIV enhancer DNA was very weak whereas a 42-residue construct, comprising the recognition helix and four copies of a positively charged segment of the repressor, bound strongly. The results of footprint and cell-free in vitro transcription studies showed that the 42-residue peptide bound preferably to the enhancer region of HIV-1 and acted as an artificial repressor. Replacement of an essential glutamine of the recognition helix by glutamic acid resulted in a partial shift of the sequence specificity of the 42-residue peptide.

Pulmonary capillary pressure and gas exchange after E. coli bacteremia in pigs

In 9 Goettingen minipigs we studied the effect of E. coli bacteremia on effective pulmonary capillary pressure and the longitudinal distribution of pulmonary vascular resistance. Precapillary pressure gradient (dPa) was calculated as the difference between mean pulmonary artery pressure (MPP) and effective pulmonary capillary pressure (Pc) (dPa = MPP-Pc), postcapillary pressure gradient (dPv) as the difference between Pc and left atrial pressure (dPv = Pc-LAP). The disturbance of pulmonary gas exchange was quantified by the AaDO2 quotient 1-PaO2/PAO2. Live E. coli infusion resulted in hypodynamic circulatory failure. Cardiac index fell from 3.7 +/- 0.81 . min-1.m-2 to 2.2 +/- 0.71 .min-1.m-2 after bacteremia lasting for 3.5 h. Simultaneously venous pulmonary vascular resistance rose from 25% of total pulmonary vascular resistance before to 32% after 3.5 h bacteremia, thus raising Pc from 11 mmHg to 16 mmHg. The degree of respiratory insufficiency was correlated with changes of MPP, dPa and dPv: 1-PaO2/PAO2 = 0.2 + 0.035.dPv (r = 0.829). Our results show, that the longitudinal distribution of pulmonary vascular resistance changes during septicemia, thus raising Pc. This may be an important factor in the genesis of septic pulmonary failure.

Evaluation of a QRS scoring system for estimating myocardial infarct size. V. Specificity and method of application of the complete system

The specificity of a previously developed 57-criteria/32-point QRS scoring system for estimating myocardial infarct (MI) size is evaluated in an extensive control population and the method of application of this system for determining a QRS score from a standard 12-lead electrocardiogram is described. Points are accumulated from Q- and R-wave durations, R- and S-wave amplitudes, R/Q- or R/S-amplitude ratios and the presence of R-wave notching, with each point representing approximately 3% of the left ventricle. The subjects were selected because of the minimal likelihood of their having had myocardial infarcts or other sources of QRS modification. There were 500 consecutively selected normal Caucasian subjects, aged 20 to 69 years, with 50 women and 50 men in each of the 5 decades. Specificity for the 57 individual criteria ranged from 89 to 100%. Fifty-one criteria met the required standard of at least 95% specificity; of the 6 that failed, 3 were successfully modified to achieve this standard and 3 were eliminated. In the resultant 54-criteria/32-point complete system, the total population, as well as both women and men, required more than 3 points to attain at least 95% specificity. Subjects in each of the 5 decades met the specificity standard either at or below the level of more than 3 points. The point score at which 95% or greater specificity was attained for the 10 age/sex subsets varied.(ABSTRACT TRUNCATED AT 250 WORDS)