Determination of baroreflex sensitivity during the modified Oxford maneuver by trigonometric regressive spectral analysis

Background

Differences in spontaneous and drug-induced baroreflex sensitivity (BRS) have been attributed to its different operating ranges. The current study attempted to compare BRS estimates during cardiovascular steady-state and pharmacologically stimulation using an innovative algorithm for dynamic determination of baroreflex gain.

Methodology/Principal Findings

Forty-five volunteers underwent the modified Oxford maneuver in supine and 60° tilted position with blood pressure and heart rate being continuously recorded. Drug-induced BRS-estimates were calculated from data obtained by bolus injections of nitroprusside and phenylephrine. Spontaneous indices were derived from data obtained during rest (stationary) and under pharmacological stimulation (non-stationary) using the algorithm of trigonometric regressive spectral analysis (TRS). Spontaneous and drug-induced BRS values were significantly correlated and display directionally similar changes under different situations. Using the Bland-Altman method, systematic differences between spontaneous and drug-induced estimates were found and revealed that the discrepancy can be as large as the gain itself. Fixed bias was not evident with ordinary least products regression. The correlation and agreement between the estimates increased significantly when BRS was calculated by TRS in non-stationary mode during the drug injection period. TRS-BRS significantly increased during phenylephrine and decreased under nitroprusside.

Conclusions/Significance

The TRS analysis provides a reliable, non-invasive assessment of human BRS not only under static steady state conditions, but also during pharmacological perturbation of the cardiovascular system.     

OXPHOS supercomplexes as a hallmark of the mitochondrial phenotype of adipogenic differentiated human MSCs

Mitochondria are essential organelles with multiple functions, especially in energy metabolism. Recently, an increasing number of data has highlighted the role of mitochondria for cellular differentiation processes. Metabolic differences between stem cells and mature derivatives require an adaptation of mitochondrial function during differentiation. In this study we investigated alterations of the mitochondrial phenotype of human mesenchymal stem cells undergoing adipogenic differentiation. Maturation of adipocytes is accompanied by mitochondrial biogenesis and an increase of oxidative metabolism. Adaptation of the mt phenotype during differentiation is reflected by changes in the distribution of the mitochondrial network as well as marked alterations of gene expression and organization of the oxidative phosphorylation system (OXPHOS). Distinct differences in the supramolecular organization forms of cytochrome c oxidase (COX) were detected using 2D blue native (BN)-PAGE analysis. Most remarkably we observed a significant increase in the abundance of OXPHOS supercomplexes in mitochondria, emphasizing the change of the mitochondrial phenotype during adipogenic differentiation.     

Distinct roles of secreted HtrA proteases from gram-negative pathogens in cleaving the junctional protein and tumor suppressor E-cadherin

The periplasmic chaperone and serine protease HtrA is important for bacterial stress responses and protein quality control. Recently, we discovered that HtrA from Helicobacter pylori is secreted and cleaves E-cadherin to disrupt the epithelial barrier, but it remained unknown whether this maybe a general virulence mechanism. Here, we show that important other pathogens including enteropathogenic Escherichia coli, Shigella flexneri, and Campylobacter jejuni, but not Neisseria gonorrhoeae, cleaved E-cadherin on host cells. HtrA deletion in C. jejuni led to severe defects in E-cadherin cleavage, loss of cell adherence, paracellular transmigration, and basolateral invasion. Computational modeling of HtrAs revealed a conserved pocket in the active center exhibiting pronounced proteolytic activity. Differential E-cadherin cleavage was determined by an alanine-to-glutamine exchange in the active center of neisserial HtrA. These data suggest that HtrA-mediated E-cadherin cleavage is a prevalent pathogenic mechanism of multiple gram-negative bacteria representing an attractive novel target for therapeutic intervention to combat bacterial infections.     

Analysis of CD97 expression and manipulation: antibody treatment but not gene targeting curtails granulocyte migration

The heptahelical receptor CD97 is a defining member of the EGF-TM7 family of adhesion class receptors. In both humans and mice, CD97 isoforms are expressed with variable numbers of tandemly arranged N-terminal epidermal growth factor-like domains that facilitate interactions with distinct cellular ligands. Results from treatment of mice with mAbs in various disease models have suggested a role for CD97 in leukocyte trafficking. Here, we aimed to thoroughly characterize the expression profile of CD97, and delineate its biological function. To this end, we applied a novel polyclonal Ab, which is the first antiserum suitable for immunohistochemistry, and combined this analysis with the study of Cd97-lacZ knock-in mice. We show that similar to the situation in humans, hematopoietic, epithelial, endothelial, muscle, and fat cells expressed CD97. Despite this broad expression pattern, the Cd97(-/-) mouse that we created had no overt phenotype, except for a mild granulocytosis. Furthermore, granulocyte accumulation at sites of inflammation was normal in the absence of CD97. Interestingly, application of CD97 mAbs blocked granulocyte trafficking after thioglycollate-induced peritonitis in wild-type but not in knock-out mice. Hence, we conclude that CD97 mAbs actively induce an inhibitory effect that disturbs normal granulocyte trafficking, which is not perturbed by the absence of the molecule.     

DC-SIGN and CD150 have distinct roles in transmission of measles virus from dendritic cells to T-lymphocytes

Measles virus (MV) is among the most infectious viruses that affect humans and is transmitted via the respiratory route. In macaques, MV primarily infects lymphocytes and dendritic cells (DCs). Little is known about the initial target cell for MV infection. Since DCs bridge the peripheral mucosal tissues with lymphoid tissues, we hypothesize that DCs are the initial target cells that capture MV in the respiratory tract and transport the virus to the lymphoid tissues where MV is transmitted to lymphocytes. Recently, we have demonstrated that the C-type lectin DC-SIGN interacts with MV and enhances infection of DCs in cis. Using immunofluorescence microscopy, we demonstrate that DC-SIGN+ DCs are abundantly present just below the epithelia of the respiratory tract. DC-SIGN+ DCs efficiently present MV-derived antigens to CD4+ T-lymphocytes after antigen uptake via either CD150 or DC-SIGN in vitro. However, DC-SIGN+ DCs also mediate transmission of MV to CD4+ and CD8+ T-lymphocytes. We distinguished two different transmission routes that were either dependent or independent on direct DC infection. DC-SIGN and CD150 are both involved in direct DC infection and subsequent transmission of de novo synthesized virus. However, DC-SIGN, but not CD150, mediates trans-infection of MV to T-lymphocytes independent of DC infection. Together these data suggest a prominent role for DCs during the initiation, dissemination, and clearance of MV infection.     

A novel form of 6-phosphofructokinase. Identification and functional relevance of a third type of subunit in Pichia pastoris

Classically, 6-phosphofructokinases are homo- and hetero-oligomeric enzymes consisting of alpha subunits and alpha/beta subunits, respectively. Herein, we describe a new form of 6-phosphofructokinase (Pfk) present in several Pichia species, which is composed of three different types of subunit, alpha, beta, and gamma. The sequence of the gamma subunit shows no similarity to classic Pfk subunits or to other known protein sequences. In-depth structural and functional studies revealed that the gamma subunit is a constitutive component of Pfk from Pichia pastoris (PpPfk). Analyses of the purified PpPfk suggest a heterododecameric assembly from the three different subunits. Accordingly, it is the largest and most complex Pfk identified yet. Although, the gamma subunit is not required for enzymatic activity, the gamma subunit-deficient mutant displays a decreased growth on nutrient limitation and reduced cell flocculation when compared with the P. pastoris wild-type strain. Subsequent characterization of purified Pfks from wild-type and gamma subunit-deficient strains revealed that the allosteric regulation of the PpPfk by ATP, fructose 2,6-bisphosphate, and AMP is fine-tuned by the gamma subunit. Therefore, we suggest that the gamma subunit contributes to adaptation of P. pastoris to energy resources.     

Does treatment of subsyndromal depression improve depression-related and diabetes-related outcomes? A randomised controlled comparison of psychoeducation,physical exercise and enhanced treatment as usual

Background

Elevated depressive symptoms that do not reach criteria for a clinical diagnosis of depression are highly prevalent in persons with diabetes. This study was aimed at determining the efficacy of psychoeducation and physical exercise compared with enhanced treatment as usual on 1-year changes in depressive symptoms, diabetes distress and self-management, and quality of life and metabolic control in type 2 diabetes patients with subsyndromal depression.

Methods

Adult type 2 diabetes patients who screened positively for depression and expressed a need for professional help with mood-related issues were eligible. Exclusion criteria were clinical depression, current psychiatric treatment and advanced diabetes complications. Out of 365 eligible patients 209 consented to either 6 weekly sessions of psychoeducation (A) and physical exercise (B), or to enhanced treatment as usual (C). Computer-generated sequences for block randomisation stratified by gender were used. Depressive symptoms (primary outcome) and diabetes distress, diabetes self-care, metabolic control and health-related quality of life (secondary outcomes) were analysed at 6-month and 12-month follow-up using repeated-measures ANOVAs.

Results

Out of the 74 patients randomised into group A, 66 into B and 69 into group C, 203 completed the interventions, and 179 patients with all 3 assessments were analysed. Depressive symptoms in participants from the psychoeducational, physical exercise and the enhanced treatment as usual groups improved equally from baseline to 12-month follow-up (time versus time x group effect; F = 12.51, p < 0.001, η² = 0.07 and F = 0.609, p = 0.656, η² = 0.007 respectively), as did diabetes distress and quality of life (all p < 0.001), diabetes self-care (p < 0.001 to < 0.05), triglycerides, and total cholesterol and LDL-cholesterol (p < 0.001).

Conclusions

The employed interventions had comparable positive effects on 12-month psychological and diabetes-related outcomes suggesting that even minimal intervention addressing patients’ diabetes-related problems and concerns had favourable clinical implications and might be sufficient to treat subsyndromal depression. Further investigation is warranted to clarify possible mechanisms of improvement.

Trial registration

Current Controlled Trials ISRCTN05673017The message on assigning the above mentioned ISRCTN was received on 11 August 2010

     

Protein-Binding RNA Aptamers Affect Molecular Interactions Distantly from Their Binding Sites

Nucleic acid aptamer selection is a powerful strategy for the development of regulatory agents for molecular intervention. Accordingly, aptamers have proven their diligence in the intervention with serine protease activities, which play important roles in physiology and pathophysiology. Nonetheless, there are only a few studies on the molecular basis underlying aptamer-protease interactions and the associated mechanisms of inhibition. In the present study, we use site-directed mutagenesis to delineate the binding sites of two 2´-fluoropyrimidine RNA aptamers (upanap-12 and upanap-126) with therapeutic potential, both binding to the serine protease urokinase-type plasminogen activator (uPA). We determine the subsequent impact of aptamer binding on the well-established molecular interactions (plasmin, PAI-1, uPAR, and LRP-1A) controlling uPA activities. One of the aptamers (upanap-126) binds to the area around the C-terminal α-helix in pro-uPA, while the other aptamer (upanap-12) binds to both the β-hairpin of the growth factor domain and the kringle domain of uPA. Based on the mapping studies, combined with data from small-angle X-ray scattering analysis, we construct a model for the upanap-12:pro-uPA complex. The results suggest and highlight that the size and shape of an aptamer as well as the domain organization of a multi-domain protein such as uPA, may provide the basis for extensive sterical interference with protein ligand interactions considered distant from the aptamer binding site.