No strong support for a Dunning-Kruger effect in creativity: analyses of self-assessment in absolute and relative terms

Competencies related to the evaluation of own cognitive processes, called metacognitive monitoring, are crucial as they help decide whether to persist in or desist from cognitive efforts. One of the most well-known phenomena in this context-the Dunning-Kruger effect-is that less skilled people tend to overestimate their performance. This effect has been reported for various kinds of performance including creativity. More recently, however, it has been suggested that this phenomenon could be a statistical artifact caused by the better-than-average effect and by regression toward the mean. Therefore, we examined the Dunning-Kruger effect in the context of creative thinking performance (i.e., divergent thinking ability) across two studies (Study 1: N = 425; Study 2: N = 317) and applied the classical quartile-based analysis as well as newly recommended, advanced statistical approaches: the Glejser test of heteroscedasticity and nonlinear quadratic regression. We found that the results indeed depended on the employed statistical method: While classical analyses supported the Dunning-Kruger effect across all conditions, it was not consistently supported by the more advanced statistical methods. These findings are in line with recent work challenging certain assumptions of the Dunning-Kruger effect and we discuss factors that undermine accurate self-assessments, especially in the context of creative performance.

Who Wants to Enhance Their Cognitive Abilities? Potential Predictors of the Acceptance of Cognitive Enhancement

With advances in new technologies, the topic of cognitive enhancement has been at the center of public debate in recent years. Various enhancement methods (e.g., brain stimulation, smart drugs, or working memory training) promise improvements in one's cognitive abilities such as intelligence and memory. Although these methods have been rather ineffective so far, they are largely available to the general public and can be applied individually. As applying enhancement might be accompanied by certain risks, it is important to understand which individuals seek to enhance themselves. For instance, individuals' intelligence, personality, and interests might predict their willingness to get enhanced. Thus, in a preregistered study, we asked 257 participants about their acceptance of various enhancement methods and tested predictors thereof, such as participants' psychometrically measured and self-estimated intelligence. While both measured and self-estimated intelligence as well as participants' implicit beliefs about intelligence, did not predict participants' acceptance of enhancement; a younger age, higher interest in science-fiction, and (partially) higher openness as well as lower conscientiousness did. Thus, certain interests and personality traits might contribute to the willingness to enhance one's cognition. Finally, we discuss the need for replication and argue for testing other potential predictors of the acceptance of cognitive enhancement.

Super-Men and Wonder-Women: the Relationship Between the Acceptance of Self-enhancement, Personality, and Values

Due to ongoing technological innovations, self-enhancement methods are publicly discussed, researched from different perspectives, and part of ethical debates. However, only few studies investigated the acceptance of these methods and its relationship with personality traits and values. The present study investigated to what extent people accept different enhancement methods and whether acceptance can be predicted by Big Five and Dark Triad traits, vulnerable narcissism, and values. In an online survey (N = 450), we measured personality traits and values. Additionally, participants read scenarios about enhancement methods and answered questions about their acceptance of these scenarios. Factor analysis indicated a general factor of acceptance across scenarios. Correlation analyses showed that high agreeableness, agreeableness-compassion, conscientiousness, conscientiousness-industriousness, and conservation- and self-transcendence values are related to less acceptance of self-enhancement. Moreover, individuals high on Dark Triad traits, vulnerable narcissism, and self-enhancement values exhibit more acceptance. Hierarchical regression analysis revealed that said values and Big Five traits explained unique variance in the acceptance of self-enhancement. These findings highlight the importance of considering personality and values when investigating self-enhancement—a topic that is receiving increasing attention by the public, politicians, and scientists.

A multi-country test of brief reappraisal interventions on emotions during the COVID-19 pandemic

The COVID-19 pandemic has increased negative emotions and decreased positive emotions globally. Left unchecked, these emotional changes might have a wide array of adverse impacts. To reduce negative emotions and increase positive emotions, we tested the effectiveness of reappraisal, an emotion-regulation strategy that modifies how one thinks about a situation. Participants from 87 countries and regions (n = 21,644) were randomly assigned to one of two brief reappraisal interventions (reconstrual or repurposing) or one of two control conditions (active or passive). Results revealed that both reappraisal interventions (vesus both control conditions) consistently reduced negative emotions and increased positive emotions across different measures. Reconstrual and repurposing interventions had similar effects. Importantly, planned exploratory analyses indicated that reappraisal interventions did not reduce intentions to practice preventive health behaviours. The findings demonstrate the viability of creating scalable, low-cost interventions for use around the world. PROTOCOL REGISTRATION: The stage 1 protocol for this Registered Report was accepted in principle on 12 May 2020. The protocol, as accepted by the journal, can be found at https://doi.org/10.6084/m9.figshare.c.4878591.v1.

Zur Situation der Jungwissenschaftlerinnen und -wissenschaftler in der Psychologie in Österreich

Zusammenfassung. Unsichere Berufsaussichten, Schwierigkeiten hinsichtlich der Work-Life-Balance und gesundheitliche Probleme werden ebenso wie eine mittlere bis hohe Arbeitszufriedenheit mit der Tätigkeit von Jungwissenschaftler_innen (JuWis) assoziiert. Da zur Situation von JuWis, die im Fach Psychologie in Österreich tätig sind, bisher keine systematischen Untersuchungen vorliegen, wurden ihre Arbeitssituation, Arbeitszufriedenheit und Beanspruchung in einer Online-Umfrage untersucht. Die Stichprobe ( N = 97) bestand aus 64 Praedocs (66 % Frauen, MAlter = 29.84 Jahre, SDAlter = 4.00 Jahre) und 33 Postdocs (55 % Frauen, MAlter = 33.39 Jahre, SDAlter = 3.41 Jahre). Die Ergebnisse zeigen eine durch verschiedene Belastungen (z. B. unsichere Karriereplanung durch befristete Verträge, eine hohe Anzahl an zusätzlichen Arbeitsstunden) gekennzeichnete Arbeitssituation von in der Psychologie tätigen JuWis. Die Arbeitszufriedenheit lag dabei im mittleren bis höheren Bereich, die Beanspruchung im mittleren bis niedrigeren Bereich. Es werden einige Bereiche mit Verbesserungspotenzial erkennbar. Aufgrund der geringen Stichprobengröße sind die Repräsentativität sowie die Generalisierbarkeit der Ergebnisse jedoch eingeschränkt. Auf Basis dieser Umfrage werden mögliche Ansatzpunkte zur Verbesserung der aktuellen Situation angeführt. Dieser Artikel soll angehenden JuWis als Orientierungshilfe dienen.

Fusion proteins consisting of Bet v 1 and Phl p 5 form IgE-reactive aggregates with reduced allergenic activity

The cross-linking of effector cell-bound IgE antibodies by allergens induces the release of inflammatory mediators which are responsible for the symptoms of allergy. We demonstrate that a recombinant hybrid molecule consisting of the major birch (Bet v 1) and grass (Phl p 5) pollen allergen exhibited reduced allergenic activity as compared to equimolar mixes of the isolated allergens in basophil activation experiments. The reduced allergenic activity of the hybrid was not due to reduced IgE reactivity as demonstrated by IgE binding experiments using sera from allergic patients. Physicochemical characterization of the hybrid by size exclusion chromatography, dynamic light scattering, negative-stain electron microscopy and circular dichroism showed that the hybrid occurred as folded aggregate whereas the isolated allergens were folded monomeric proteins. IgG antibodies raised in rabbits against epitopes of Bet v 1 and Phl p 5 showed reduced reactivity with the hybrid compared to the monomeric allergens. Our results thus demonstrate that aggregation can induce changes in the conformation of allergens and lead to the reduction of allergenic activity. This is a new mechanism for reducing the allergenic activity of allergens which may be important for modifying allergens to exhibit reduced side effects when used for allergen-specific immunotherapy.

The self-other knowledge asymmetry in cognitive intelligence, emotional intelligence, and creativity

The self–other knowledge asymmetry model (SOKA) assumes that some personality traits might be open to oneself and other persons (‘open area’), while other traits are more accurately perceived by others (‘blind spot’); a third group of traits might be visible only to oneself and not to others (‘hidden area’), and finally a trait might neither be visible to oneself nor to one's peers (‘unknown area’). So far, this model has been tested only for personality traits and general intelligence, not for more specific abilities; to do so was the novel intention of our study. We tested which of six abilities (verbal, numerical, and spatial intelligence; interpersonal and intrapersonal competence; and creative potential/divergent thinking ability) are in which SOKA area. We administered performance tests for the six abilities in two samples – 233 14-year-olds and 215 18-year-olds – and collected self- and peer-ratings for each domain. Numerical intelligence and creativity were judged validly both from self- and peer-perspectives (‘open area’). In the younger sample verbal intelligence was validly estimated only by peers (‘blind spot’), whereas the older group showed some insight into their own abilities as well (‘blind spot’ to ‘open area’). While in the younger group only the pupils themselves could validly estimate their intra- and interpersonal competence (‘hidden area’), in the older group peers were also successful in estimating other's interpersonal competence, albeit only with low accuracy (‘hidden area’ to ‘open area’). For 18-year-olds, spatial ability was in the hidden area too, but in 14-year-olds this could neither be validly estimated by pupils themselves nor by peers (‘unknown area’). These results implicate the possibility of non-optimal career choices of young people, and could, therefore, be helpful in guiding professional career counselling.

Similar localization of conformational IgE epitopes on the house dust mite allergens Der p 5 and Der p 21 despite limited IgE cross-reactivity

BACKGROUND

Due to high IgE recognition frequency and high allergenic activity, Der p 5 and Der p 21 are clinically important house dust mite (HDM) allergens. The objective of this study was to characterize the immunodominant IgE epitopes of Der p 5 and Der p 21 responsible for their high allergenic activity.

METHODS

A panel of 12 overlapping peptides spanning the Der p 5 and Der p 21 sequence were synthesized to search for sequential IgE epitopes by direct testing for allergic patients' IgE reactivity. Peptide-specific antibodies raised in rabbits were used in inhibition studies for localizing conformational IgE epitopes which were visualized on the surfaces of the allergen structures by molecular modelling. IgE cross-reactivity between the allergens was investigated by IgE inhibition studies.

RESULTS

Immunodominant IgE epitopes defined by allergic patients' IgE on Der p 5 and Der p 21 were primarily of the conformational, discontinuous type including N- and C-terminal portions of the protein. They could be located on each allergen on one area with similar localization, but despite similar structure of the allergens, no relevant IgE cross-reactivity could be detected.

CONCLUSION

Our study shows that Der p 5 and Der p 21 contain a major conformational IgE epitope-containing area located on similar portions of their structure, but they lack relevant IgE cross-reactivity. These data are important for the development of modern allergy vaccines based on defined molecules for allergen-specific immunotherapy of HDM allergy.

Isolation of a high-affinity Bet v 1-specific IgG-derived ScFv from a subject vaccinated with hypoallergenic Bet v 1 fragments

Background

Recombinant hypoallergenic allergen derivatives have been used in clinical immunotherapy studies, and clinical efficacy seems to be related to the induction of blocking IgG antibodies recognizing the wild‐type allergens. However, so far no treatment‐induced IgG antibodies have been characterized.

Objective

To clone, express, and characterize IgG antibodies induced by vaccination with two hypoallergenic recombinant fragments of the major birch pollen allergen, Bet v 1 in a nonallergic subject.

Methods

A phage‐displayed combinatorial single‐chain fragment (ScFv) library was constructed from blood of the immunized subject and screened for Bet v 1‐reactive antibody fragments. ScFvs were tested for specificity and cross‐reactivity to native Bet v 1 and related pollen and food allergens, and epitope mapping was performed. Germline ancestor genes of the antibody were analyzed with the ImMunoGeneTics (IMGT) database. The affinity to Bet v 1 and cross‐reactive allergens was determined by surface plasmon resonance measurements. The ability to inhibit patients’ IgE binding to ELISA plate‐bound allergens and allergen‐induced basophil activation was assessed.

Results

A combinatorial ScFv library was obtained from the vaccinated donor after three injections with the Bet v 1 fragments. Despite being almost in germline configuration, ScFv (clone H3‐1) reacted with high affinity to native Bet v 1 and homologous allergens, inhibited allergic patients’ polyclonal IgE binding to Bet v 1, and partially suppressed allergen‐induced basophil activation.

Conclusion

Immunization with unfolded hypoallergenic allergen derivatives induces high‐affinity antibodies even in nonallergic subjects which recognize the folded wild‐type allergens and inhibit polyclonal IgE binding of allergic patients.

Loss of plant biodiversity eliminates stimulatory effect of elevated CO2 on earthworm activity in grasslands

Earthworms are among the world's most important ecosystem engineers because of their effects on soil fertility and plant productivity. Their dependence on plants for carbon, however, means that any changes in plant community structure or function caused by rising atmospheric CO2 or loss of plant species diversity could affect earthworm activity, which may feed back on plant communities. Production of surface casts measured during three consecutive years in field experimental plots (n = 24, 1.2 m(2)) planted with local calcareous grassland species that varied in plant species richness (diversity levels: high, 31 species; medium, 12; low, 5) and were exposed to ambient (356 μl CO2 l(-1)) or elevated (600 μl CO2 l(-1)) CO2 was only consistently stimulated in high diversity plots exposed to elevated CO2 (+120 %, 31 spp: 603 ± 52 under ambient CO2 vs. 1,325 ± 204 g cast dwt. m(-2) year(-1) under elevated CO2 in 1996; +77 %, 940 ± 44 vs. 1,663 ± 204 g cast dwt. m(-2) year(-1) in 1998). Reductions in plant diversity had little effect on cast production in ecosystems maintained at ambient CO2, but the stimulatory effect of elevated CO2 on cast production disappeared when plant species diversity was decreased to 12 and 5 species. High diversity plots were also the only communities that included plant species that an earlier field study showed to be among the most responsive to elevated CO2 and to be most preferred by earthworms to deposit casts near. Further, the +87 % CO2-induced increase in cast production measured over the 3 years corresponded to a parallel increase in cumulative total nitrogen of 5.7 g N m(-2) and would help explain the large stimulation of aboveground plant biomass production observed in high-diversity communities under elevated CO2. The results of this study demonstrate how the loss of plant species from communities can alter responses of major soil heterotrophs and consequently ecosystem biogeochemistry.

Neuropeptide Y modulates steroid production of human adrenal H295R cells through Y1 receptors

Neuropeptide Y (NPY) is abundantly expressed in the nervous system and acts on target cells through NPY receptors. The human adrenal cortex and adrenal tumors express NPY receptor subtype Y1, but its function is unknown. We studied Y1-mediated signaling, steroidogenesis and cell proliferation in human adrenal NCI-H295R cells. Radioactive ligand binding studies showed that H295R cells express Y1 receptor specifically. NPY treatment of H295R cells stimulated the MEK/ERK1/2 pathway, confirming that H295R cells express functional Y1 receptors. Studies of the effect of NPY and related peptide PYY on adrenal steroidogenesis revealed a decrease in 11-deoxycortisol production. RIA measurements of cortisol from cell culture medium confirmed this finding. Co-treatment with the Y1 antagonist BIBP2336 reversed the inhibitory effect of NPY on cortisol production proving specificity of this effect. At mRNA level, NPY decreased HSD3B2 and CYP21A2 expression. However NPY revealed no effect on cell proliferation. Our data show that NPY can directly regulate human adrenal cortisol production.

Nitric oxide inhibits growth of glomerular mesangial cells: role of the transcription factor EGR-1

Nitric oxide inhibits growth of glomerular mesangial cells: Role of the transcription factor Egr-1.

BACKGROUND

In previous studies, we found a close link of early growth response gene-1 (Egr-1) expression to mesangial cell (MC) proliferation. Antiproliferative agents inhibited mitogen-induced Egr-1 expression. Here we investigated the effect of S-nitrosoglutathione (GSNO) on the proliferation of MCs, specifically asking how GSNO regulates the transcription factor Egr-1, which we have previously shown to be critical for the induction of MC mitogenesis.

METHODS

The proliferation of MCs was measured by thymidine incorporation and cell counting. Egr-1 mRNA and protein levels were detected by Northern and Western blots. Electrophoretic mobility shift assays (EMSAs) and chloramphenicol acetyltransferase (CAT) assays were performed to test whether GSNO modulates DNA binding and transcriptional activation of Egr-1.

RESULTS

GSNO strongly inhibited serum-induced MC proliferation (-84% at 1 mmol/L). A mild inhibition of serum-induced Egr-1 mRNA was observed at GSNO concentrations from 50 to 200 micromol/L, whereas mRNA levels increased again at concentrations above 500 micromol/L. This increased mRNA expression, however, was not translated into Egr-1 protein. Instead, Egr-1 protein induction was inhibited (-40%). EMSAs indicated that GSNO inhibited specific binding of Egr-1 to its DNA consensus sequence. Moreover, transcriptional activation by Egr-1 in CAT assays using a reporter plasmid bearing three Egr-1 binding sites was strongly suppressed by GSNO.

CONCLUSIONS

Our data identify GSNO as a potent inhibitor of MC growth with potential beneficial effects in proliferative glomerular diseases. This antimitogenic property is mediated at least in part by inhibitory effects of GSNO on Egr-1 protein levels and by reducing the ability of Egr-1 to activate transcription by impairing its DNA binding activity.

Lysophosphatidic acid-mediated signal-transduction pathways involved in the induction of the early-response genes prostaglandin G/H synthase-2 and Egr-1: a critical role for the mitogen-activated protein kinase p38 and for Rho proteins

During inflammatory processes of the kidney, lesions of the glomerulus lead to aggregation of thrombocytes and infiltration of macrophages, which can release bioactive mediators. One of these important signalling molecules is lysophosphatidic acid (LPA). Incubation of rat mesangial cells with LPA induced mRNA and protein expression of the early-response genes pghs-2 (for prostaglandin G/H synthase-2/cyclo-oxygenase-2) and egr-1. As shown by antisense experiments, induction of egr-1 was related to the strong mitogenic effect of LPA. LPA-mediated gene expression was inhibited by pertussis toxin, indicating coupling to G-proteins of the Gi family. Specific inhibition of proteins of the small G-protein subfamily Rho with toxin B from Clostridium difficile led to changes in mesangial cell morphology without induction of apoptosis. LPA-mediated expression of pghs-2 and egr-1 was reduced to base-line levels by toxin B, indicating a role for Rho proteins in LPA-mediated gene induction. Of the two mitogen-activated protein kinase (MAPK) pathways investigated, the MAPK kinase-extracellular signal-regulated kinase pathway was involved in the induction of both pghs-2 and egr-1 mRNA expression, as shown by the inhibitory effect of PD98059. Activation of the MAPK p38, however, was only related to pghs-2 expression, whereas egr-1 expression was not affected by treatment of mesangial cells with the specific inhibitor SB203580. Taken together our data provide evidence that LPA-mediated activation of MAPK kinase and Rho proteins leads to the induction of the functionally distinct early-response genes pghs-2 and egr-1, whereas activation of MAPK p38 revealed considerable differences between the regulation of these two genes.

LDL-mediated interaction of Lp[a] with HepG2 cells: a novel fluorescence microscopy approach

We studied the topography of Lp[a]-LDL-cell interactions by means of fluorescence microscopy, using fluorescence-labeled lipoproteins. In contrast to known methods which are based on noncovalent labeling of lipoproteins by positively charged amphiphiles, the protein moiety of LDL and Lp[a] was covalently labeled with either BODIP-succinimide-ester (green) or rhodamine X iodoacetamide (red). The interaction of the fluorescent lipoproteins with cultured HepG2 cells was studied using a confocal laser scanning fluorescence microscope. LDL and Lp[a], each labeled with a different dye, could be examined separately within a mixture of both lipoproteins during their interaction with HepG2 cells. At 4 degrees C, the majority of both fluorescent particles co-localized and only a few separate LDL- or Lp[a]-binding domains could be observed. Quantification of the amount of fluorescent lipoprotein associated with the cell surface at 4 degrees C showed that binding of Lp[a] was increased in the presence of LDL under these conditions, probably via formation of an Lp[a]-LDL complex. At 37 degrees C, LDL and Lp[a] were taken up by the cells within 10 min. Again the majority of LDL and Lp[a] particles co-localized intracellularly. Only minor amounts of LDL and Lp[a] could be observed separately. As the entire fluorescence of labeled Lp[a] co-localized with excess of LDL in cells, and taking into account the high tendency of LDL-Lp[a] association in solution and on cell surfaces, it is concluded that a significant portion of the internalized Lp[a] is taken up into the cells by the LDL receptor via LDL by a hitchhiking-like process.

[Egr-1 transcription factor regulates the growth of glomerular mesangium cells]

BACKGROUND

The transcriptional regulator Early growth response gene-1 (Egr-1) is rapidly and transiently induced by various mitogens in cultured rat mesangial cells (MCs).

METHOD AND RESULTS

Here we show Egr-1 induction in an in vivo model of mesangioproliferative glomerulonephritis (GN). A 14.9-fold increase in Egr-1 mRNA was observed 6 days after disease induction. A concomitant increase in Egr-1 protein was demonstrated by immunocytochemistry. Egr-1 was mainly localized to the nuclei of cells in mesangial localization. To test whether Egr-1 directly regulated MC proliferation, we preincubated cultured MCs with antisense oligonucleotides directed against Egr-1. The platelet-derived growth factor (PDGF)-induced increase in Egr-1 mRNA and protein levels was inhibited by 75% and 74%, respectively. At the same time Egr-1 antisense oligonucleotides dose-dependently inhibited MC-proliferation as determined by thymidine-uptake by up to 75%. Control oligonucleotides were without effects on Egr-1 mRNA, protein or MC growth.

CONCLUSION

We conclude that Egr-1 induction is a necessary step in the mitogenic signaling cascade in glomerular MCs.

Transcription factor Egr-1 regulates glomerular mesangial cell proliferation

Increase of glomerular mesangial cells (MCs) is a prominent histopathological finding in many types of glomerulonephritis. We have shown previously that expression of the zinc-finger transcription factor, early growth response gene-1 (egr-1), is closely correlated with the proliferation of cultured MCs. To elucidate whether Egr-1 is required for MC proliferation, we inhibited serum-induced Egr-1 expression by phosphothioate-modified antisense oligonucleotides (ODNs). Uptake of antisense ODNs into MCs was demonstrated, and five different egr-1 antisense ODNs were tested for their impact on serum-induced egr-1 mRNA and protein levels and on MC growth. The most potent egr-1 antisense ODN inhibited serum-induced egr-1 mRNA by 68%, protein induction by 58%, and MC replication as measured by [3H]thymidine uptake and cell counts by 78 and 46%, respectively. The effects of antisense ODNs on MC growth correlated closely with their ability to inhibit Egr-1 protein. ODNs acted in a dose-dependent manner, the minimal effective concentration being 1 microM. Control ODNs had no significant effects. In addition, antisense ODNs against egr-1 potently inhibited endothelin-1-induced Egr-1 expression and MC growth. Heparin, a known inhibitor of MC growth, suppressed serum-induced [3H]thymidine uptake by 39% and egr-1 mRNA expression by 44%. We conclude that Egr-1 is an essential part of the mitogenic signal transduction cascade in cultured MCs.

Oxidation of fluorescent glycero- and sphingophospholipids in human plasma lipoproteins: alkenylacyl subclasses are preferred targets

OBJECTIVES

Oxidation of polyunsaturated fatty acids in lipoproteins is supposed to play a crucial role at the early stages of atherogenesis. The polyunsaturated lipids (PUFAs) become oxidized and, thus, the degree and rate of lipid oxidation depend on their concentration and, probably, on the lipid moiety to which they are attached.

DESIGN AND METHODS

To determine the relative oxidation susceptibilities of sphingo- and glycerolipid-bound fatty acyl chains, we used fluorescent analogs of the respective compounds, in which one natural fatty acyl chain was replaced by fluorescent diphenylhexatriene propionic acid.

RESULTS

Oxidation susceptibilities of the fluorescent acyl chains in the presence of Cu2+ or AAPH depended, in general, on the phospholipid to which they were bound and the lipoprotein. Phospholipids were oxidized faster in HDL than in LDL or Lp(a). Plasmalogens were more susceptible to oxidation than phosphatidylcholine and sphingomyelin.

CONCLUSION

Thus, HDL and plasmalogens may be considered as preferred targets of lipid oxidation before the bulk of polyunsaturated phospholipids (mainly phosphatidylcholine) in LDL is subject to free radical attack.

Concentrations of various arachidonic acid metabolites in menstrual fluid are associated with menstrual pain and are influenced by hormonal contraceptives

In a pilot study we investigated the association between concentrations of various eicosanoids in menstrual blood with pain and oral contraceptive use. Menstrual fluid was collected on tampons by 12 women who did not use an oral contraceptive but suffered from slight primary dysmenorrhea and by three pain-free women who used an oral contraceptive. Eicosanoids (cyclooxygenase products: 6-ketoprostaglandin F1 alpha, thromboxane B2, prostaglandin E2, prostaglandin F2 alpha, 13,14-dihydro-15-ketoprostaglandin F2 alpha, 12-hydroxy-heptadecatrienoic acid; lipoxygenase products: 5-, 12-, 15-hydroxy-eicosatetraenoic acid (HETE), leukotriene B4, leukotriene C4, leukotriene D4, leukotriene E4) and female sex steroids (17 beta-estradiol and progesterone) were analyzed by the combined use of high-performance liquid chromatography and radioimmunoassay. 12-HETE was the main arachidonic acid metabolite. An increased metabolism of arachidonic acid was associated with pain, especially when synthesis of 12-HETE was elevated. Oral contraceptive use decreased the synthesis of prostaglandins as well as leukotrienes. The concordant changes of cyclooxygenase and lipoxygenase products in dysmenorrhea or in oral contraceptive use may be explained by an increased or decreased phospholipid metabolism, respectively.

A new fluorescence method for the continuous determination of surface lipid oxidation in lipoproteins and plasma

We report on a new method for the determination of lipid oxidation in lipoproteins and plasma. The biological lipid system is preloaded with a fluorescent analog of phosphatidylcholine containing diphenylhexatriene (DPH) propionic acid covalently linked to the sn-2 position. When externally added, the respective phospholipid label (DPHPC) localizes to the surface monolayer of a lipoprotein. Under oxidative conditions (e.g. in the presence of Cu2+ ions) the fluorophore undergoes decomposition, resulting in a continuous decrease of fluorescence intensity which reflects the oxidation of a chemically defined phospholipid molecule with well defined localization. When incorporated into LDL particles, the kinetics of the decrease in DPHPC fluorescence intensity upon exposure to Cu2+ us very similar to that of conjugated diene accumulation. Furthermore, our assay can be applied to follow the oxidation of lipids in diluted serum and may also be developed into a suitable test system for clinical studies of susceptibility of plasma lipids to oxidation.

Transfer of phospholipase A-resistant pyrene-dialkyl-glycerophosphocholine to plasma lipoproteins: differences between Lp[a] and LDL

1-O-Hexadecyl-2-O-pyrenedecanyl-sn-glycero-3-phosphocholine, a non-hydrolyzable fluorescent diether analog of phosphatidylcholine (PC), was synthesized as a probe for studying phospholipid transfer to different lipoprotein classes with potential phospholipase activities. After incubation of total human plasma with the new probe at 37 degrees C for 4.5 h, a characteristic partition between the main lipoprotein fractions was observed. The fluorescent lipid was not degraded under these conditions and, therefore, served as a measure for choline glycerophospholipid distribution between plasma lipoproteins. In low density lipoprotein (LDL) and high density lipoprotein-3 (HDL3) the fluorescent PC analog showed only monomer fluorescence, whereas in Lp[a] and HDL2 monomer and excimer fluorescence were observed, indicating that the fluorescent phosphatidylcholine analog was incorporated into the respective lipoproteins to a different extent. According to the increased pyrene excimer fluorescence in Lp[a] compared with LDL the labeled phosphatidylcholine must be enriched and/or clustered in Lp[a]. Data from phospholipid and total fluorescence analyses are compatible with the assumption of higher label concentration in Lp[a]. On the other hand, transfer rates for serum protein-catalyzed lipid transport into isolated Lp[a] were slower as compared to LDL. It is suggested that slower lipid transfer to Lp[a] under these conditions is due to the decreased lipid mobility in the Lp[a] surface, whereas the higher extent of label partition into Lp[a] as observed in total plasma might be due to the higher affinity of apolipoproteins for phosphatidylcholine in Lp[a] (Sommer, A., et al. 1992. J. Biol. Chem. 267: 24217-24222). The use of a fluorescent dialkyl- instead of diacyl-glycerophosphocholine for transfer studies was mandatory, as we found that lipoproteins contained phospholipase A2 activity toward long-chain phosphatidylcholine. The lipoprotein-associated phospholipase A2 was three times more active in Lp[a] than in LDL. The degradation products formed by the phospholipase, fatty acids, and lyso-PC may add to the high atherogenic potential of Lp[a].

Insulin-responsive regions of the rat fatty acid synthase gene promoter

Here we show that insulin may play a role in the diet-induced regulation of the rat fatty acid synthase (FAS; EC 2.3.1.85). Transient transfection of human and rat hepatoma cell lines with successively deleted FAS/CAT promoter fusion plasmids was used to determine the effect of insulin on FAS promoter activity. Our results indicate the existence of cis-acting insulin-responsive elements in the FAS promoter; the position of one of these is coincident with the position of a previously determined diet-induced DNAse I hypersensitive site (HSi-1) at approximately -500 bp relative to the transcription start site of FAS mRNA.

Measurement of eicosanoids in menstrual fluid by the combined use of high pressure chromatography and radioimmunoassay

Methods are described for the quantification of various eicosanoids (cyclooxygenase products: 6-KETO, TXB2, PGE2, PGF2 alpha, DHK; lipoxygenase products: 5-, 12-, 15-HETE, LTB4, LTC4, LTD4, LTE4) in menstrual blood collected by tampons. Samples were extracted with acidified ethanol. After purification by SEP-PACK C18 columns, the compounds were separated by reversed phase HPLC using a ternary gradient system. The eicosanoid concentrations of the fractionated eluents were measured by radioimmunoassay and corrected for recovery. 12-HETE was the most prominent metabolite of arachidonic acid in menstrual blood (mean: 1174 ng/g blood). With the exception of PGF2 alpha and TXB2 (mean: 343 and 212 ng/g blood, respectively) other eicosanoids were detected in remarkable lower concentrations.

Specific and non specific stimulation of prostaglandin release by human skin fibroblasts in culture.--Are changes of membrane fluidity involved?

In order to study a bidirectional relationship between changes of membrane fluidity and prostaglandin synthesis, the arachidonic acid cascade was stimulated in cultured human skin fibroblasts by unspecific stimuli (hypotonicity, low calcium concentrations) and by the specific stimulus, bradykinin. Fluorescence anisotropy of trimethylammoniumdiphenylhexatriene was used to measure membrane fluidity in cell monolayers. Hypotonicity or low calcium concentrations induce membrane fluidisation and prostaglandin synthesis. However, after specific stimulation of prostaglandins with bradykinin (at normocalcic and isotonic conditions) a rigidification of plasma membranes was observed in living cells. Fluidisation of membranes and bradykinin activate phospholipase A2 and induce prostaglandin synthesis. Although in cell membrane preparations increased phospholipase A2 activity leads to fluidisation, in our model a membrane fluidisation was not observed after stimulation of phospholipase with bradykinin. This suggests that in living cells a fluidizing effect of lysolecithin resulting from phospholipase A2 activation may be rapidly counteracted by its removal. A decrease of phosphatidylcholin content and consequently a rigidification of the membrane may ensue. Thus, the cell culture model using two different ways of stimulating phospholipase activity, helps to define the directional relationship between changes of membrane fluidity and activation of phospholipase and the arachidonic acid cascade in living human cells.

Radioimmunoassay for immunoreactive non-collagenous domain of type IV collagen (NC1) in serum: normal pregnancy and preeclampsia

The use of a magnetic separation agent in a modified radioimmunoassay for the non-collagenous cross-linked region (NC1) of basement membrane collagen is described. The rabbit anti-NC1 serum employed in the assay revealed a binding behaviour similar to that reported recently (Mark et al. (1985) Eur. J. Biochem. 146, 555-562; Schuppan et al. (1986) J. Clin. Invest. 78, 241-248) with respect to the integrity of NC1-disulphide bridges, affinity to NC1 subunits and lack of reactivity with other determinants of type IV collagen. Immunoreactive serum NC1, which increased towards the end of gestation, showed a broad peak during the second trimester of pregnancy. In preeclampsia, immunoreactive serum-NC1 was slightly elevated.