The effect of erroneous responses on response monitoring in patients with major depressive disorder: a study with event-related potentials

Perceived failure is reported to have detrimental effects on subsequent performance in patients with major depressive disorder. We investigated the error-related negativity (ERN)/error negativity (Ne), an electrophysiological correlate of response monitoring, using a 64-channel EEG. Sixteen patients with DSM-IV major depressive disorder and 16 matched controls participated in an Eriksen flanker task with continuous performance feedback that signaled monetary reward. Compared to controls, patients with major depressive disorder showed a less negative ERN/Ne in error trials following error trials. This result might reflect impaired response monitoring processes in major depressive disorder resulting from an underactivity in a central reward pathway and/or a deficit in strategic reasoning.     

Three-dimensional in vitro model of adipogenesis: comparison of culture conditions

In vivo and in vitro studies have demonstrated both promise and current limitations in tissue engineering of fat. Herein, we report the establishment of a well-defined three-dimensional (3-D) in vitro model useful for systematic investigations of 3-D adipogenesis. Polyglycolic acid fiber meshes were dynamically seeded with 3T3-L1 preadipocytes; subsequently, cell-polymer constructs were hormonally induced and cultivation under three different conditions was evaluated. Regarding tissue coherence and intracellular lipid content, culture of cell-polymer constructs either dynamically in well plates or in stirred bioreactors yielded similar results, which were distinctly improved compared with static conditions in well plates. At the protein and mRNA levels, significantly increased expression of genes characteristic for a mature adipose phenotype was demonstrated for constructs dynamically cultured in well plates, as compared with static conditions. Furthermore, investigation of lipolysis under stimulating and inhibiting conditions demonstrated functionality of the dynamically differentiated constructs. Using dynamic culture conditions, the presented in vitro model system is suggested as a valuable tool serving both fat tissue engineering and basic research by facilitating investigations of tissue-inherent features not possible under conventional 2-D culture conditions.     

Mutations of FBN1 and genotype-phenotype correlations in Marfan syndrome and related fibrillinopathies

The Marfan syndrome (MFS) is a pleiotropic, autosomal dominant disorder of connective tissue with highly variable clinical manifestations including aortic dilatation and dissection, ectopia lentis, and a series of skeletal anomalies. Mutations in the gene for fibrillin-1 (FBN1) cause MFS, and at least 337 mainly unique mutations have been published to date. FBN1 mutations have been found not only in MFS but also in a range of connective tissue disorders collectively termed fibrillinopathies ranging from mild phenotypes, such as isolated ectopia lentis, to severe disorders including neonatal MFS, which generally leads to death within the first two years of life. The present article intends to provide an overview of mutations found in MFS and related disorders and to discuss potential genotype-phenotype correlations in MFS.     

Efficient maturation and cytokine production of neonatal DCs requires combined proinflammatory signals

Specific functional properties of dendritic cells (DCs) have been suspected as being responsible for the impaired specific immune responses observed in human neonates. To analyze stimulatory requirements for the critical transition from immature, antigen-processing DCs to mature, antigen-presenting DCs, we investigated the effect of different proinflammatory mediators and antigens on phenotype and cytokine secretion of human neonatal DCs derived from hematopoietic progenitor cells (HPCs). Whereas single proinflammatory mediators were unable to induce the maturation of neonatal DCs, various combinations of IFNgamma, CD40L, TNFalpha, LPS and antigens, induced the maturation of neonatal DCs documented by up-regulation of HLA-DR, CD83 and CD86. Combinations of proinflammatory mediators also increased cytokine secretion by neonatal DCs. Especially combined stimulation with LPS and IFNgamma proved to be very efficient in inducing maturation and cytokine synthesis of neonatal DCs. In conclusion, neonatal DCs can be stimulated to express maturation as well as costimulatory surface molecules. However, induction of maturation requires combined stimulation with multiple proinflammatory signals.     

Mouse models of atopic eczema critically evaluated

Atopic eczema (AE) is a chronic relapsing inflammatory skin disorder with increasing prevalence in Western societies. Even though we have made considerable progress in understanding the cellular and molecular nature of cutaneous inflammation, the precise pathomechanisms of AE still remain elusive. Experimental animal models are indispensable tools to study the pathogenic mechanisms and to test novel therapeutic approaches in vivo. For AE a considerable number of mouse models have been proposed and have been used to study specific aspects of the disease, such as genetics, skin barrier defects, immune deviations, bacteria-host interactions or the role of cytokines or chemokines in the inflammatory process. While some models closely resemble human AE, others appear to reflect only specific aspects of the disease. Here we review the currently available mouse models of AE in light of the novel World Allergy Organization classification of eczematous skin diseases and evaluate them according to their clinical, histopathological and immunological findings. The pathogenetic analogies between mice and men will be discussed.     

Ionic conductances of cultured principal cell epithelium of renal collecting duct

The ionic conductive properties were studied of epithelia of collecting duct principal cells which had been grown in primary tissue culture from renal cortex/capsule explants. When pretreated with aldosterone (10^–6 mol/l) and bathed on either surface with isotonic HCO ₃ ^– -free Ringer's solution, the transepithelial voltage,V _te, varied between –21 and –72 mV (apical surface negative) while the transepithelial resistance,R _te, ranged from 0.4 to 1.5 kcm². By 10:1 step-changes in Na⁺ concentration the apical cell membrane was shown to have a high conductivity for sodium, inhibitable by amiloride, 10^–6 mol/l. However, contrary to observations in natural collecting duct under control conditions, amiloride never reversed the polarity ofV _te even at 10^–4 mol/l. Both the apical and the basolateral cell membranes were conductive for potassium and both conductivities were inhibitable by Ba²⁺ (5 mmol/l). 10:1 reduction of apical Cl^– concentration strongly hyperpolarizedV _te with a monophasic time course suggesting the presence of a paracellular shunt conductance for Cl^–. In addition there may be a small Cl^– conductance present in the apical cell membrane since apical application of the chloride channel blocker 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPAB) at 10^–7 mol/l produced a minute but significant hyperpolarization. On the other hand, 10:1 reduction of basolateral Cl^– concentration caused a biphasic change inV _te (initial depolarization, followed by repolarization) which indicates the presence of a large Cl^– conductance in the basolateral cell membrane. The latter was not inhibitable by 10^–7 mol/l NPPAB. Higher concentrations of this and of an other Cl^– channel blocker produced non-specific effects. In conclusion, our studies of a pure principal cell epithelium confirm findings described for the intact cortical collecting duct and add new information concerning chloride conductivity and related blocking agents.Dedicated to Prof. Dr. H. Sitte, Homburg, FRG, upon his 60th birthday.     

CD4+ and CD8+ cells in cryopreserved human PBMC maintain full functionality in cytokine ELISPOT assays

The frequency and the cytokine signature of antigen-specific T cells in the blood reflect the magnitude and the quality of T cell immunity in vivo. Recently, cytokine enzyme-linked immunospot (ELISPOT) assays performed on freshly isolated peripheral blood mononuclear cells (PBMC) emerged as a promising tool for monitoring these key parameters, providing direct feedback information on the efficacy of vaccinations and immune therapies. However, performing ELISPOT assays with freshly isolated cells is not readily feasible in the context of clinical trials. The ability to obtain valid ELISPOT data on cryopreserved samples would greatly enhance ex vivo immune monitoring capabilities. We have therefore systematically studied antigen-specific T cell responses in freshly isolated PBMC and after cryopreservation. Four healthy donors were selected that displayed T cell responses to six recall antigens. The antigen reactive T cells were defined as CD4 or CD8 cells, and their cytokine effector class was established measuring interferon (IFN)-gamma, interleukin (IL)-2, IL-4 and IL-5. The donors were bled at three different time points, and their PBMC were tested fresh and after freeze-thawing. The results showed that the frequencies and type 1/type 2 cytokine signatures of recall antigen-specific CD4 and CD8 cells are unaffected after cryopreservation. In contrast to these data obtained on human PBMC, cryopreservation of murine spleen cells causes a decrease in cytokine secretion.