Effects of obesity on endothelium-dependent reactivity during acute nitric oxide synthase inhibition: modulatory role of endothelin.

This study investigated vascular reactivity in response to acetylcholine, in the presence of acute inhibition of nitric oxide synthase, in the carotid artery and aorta of obese C57Bl6/J mice fed on a high-fat diet for 30 weeks, and of control mice. A subgroup of obese animals was also treated with the ET(A) receptor antagonist darusentan (50 mg x kg(-1) x day(-1)). In vascular rings from control animals, acetylcholine caused endothelium-dependent contractions in the carotid artery, but not in the aorta. In vascular rings from obese mice, contractility to acetylcholine was also evident in the aorta, and that in the carotid artery was increased compared with control mice. ET(A) receptor blockade by darusentan treatment of the obese mice prevented enhanced vasoconstriction to acetylcholine, resulting in mild vasodilatation. Thus obesity increases endothelium-dependent vasoconstriction in the absence of endothelial nitric oxide. This effect can be completely prevented by chronic ET(A) receptor blockade, suggesting that endothelin modulates increased endothelium-dependent vasoconstriction in obesity.

Occupational role stress is associated with higher cortisol reactivity to acute stress

We investigated whether occupational role stress is associated with differential levels of the stress hormone cortisol in response to acute psychosocial stress. Forty-three medication-free nonsmoking men aged between 22 and 65 years (mean ± SEM: 44.5 ± 2) underwent an acute standardized psychosocial stress task combining public speaking and mental arithmetic in front of an audience. We assessed occupational role stress in terms of role conflict and role ambiguity (combined into a measure of role uncertainty) as well as further work characteristics and psychological control variables including time pressure, overcommitment, perfectionism, and stress appraisal. Moreover, we repeatedly measured salivary cortisol and blood pressure levels before and after stress exposure, and several times up to 60 min thereafter. Higher role uncertainty was associated with a more pronounced cortisol stress reactivity (p = .016), even when controlling for the full set of potential confounders (p < .001). Blood pressure stress reactivity was not associated with role uncertainty. Our findings suggest that occupational role stress in terms of role uncertainty acts as a background stressor that is associated with increased HPA-axis reactivity to acute stress. This finding may represent a potential mechanism regarding how occupational role stress may precipitate adverse health outcomes.

The growing galectin network in colon cancer and clinical relevance of cytoplasmic galectin-3 reactivity

BACKGROUND/AIM Human lectins translate sugar-encoded signals of cell surface glycoconjugates into biological effects, and this is what is known for the adhesion/growth-regulatory galectins. In addition, the multifunctional members of this group can be intracellular, binding to distinct proteins. The presence of galectins and galectin reactivity were exemplarily studied in the present article. MATERIALS AND METHODS We combined immuno- and lectin histochemical monitoring in colon cancer on tissue arrays. RESULTS Intracellular presence of galectins-7 and -9 in colon cancer is detected, extending the previously known set of five expressed lectins this tumor type. The assumed significance of intracellular galectin presence, e.g. for an interplay with BCL2, β-catenin, oncogenic KRAS or synexin, is underscored by respective staining with labeled galectin-3. Statistical significance was obtained for galectin-3 staining with respect to tumor differentiation (p=0.0376), lymph node metastasis (p=0.0069) and lymphatic invasion (p=0.0156). Survival was correlated to staining, galectin-3 reactivity indicating a favorable prognosis (p=0.0183), albeit not as an independent marker. No correlation to KRAS/BRAF status was detected. CONCLUSION These results encourage further testing of labeled human galectins as probes and immunohistochemical fingerprinting instead of measuring single or few activities, in colon cancer and other tumor types.

Procoagulant reactivity to laboratory acute mental stress in Africans and Caucasians, and its relation to depressive symptoms: the SABPA study.

The risk of cardiovascular disease is dramatically increasing in Africans (black). The prothrombotic stress response contributes to atherothrombotic disease and is modulated by depressive symptoms. We examined coagulation reactivity to acute mental stress and its relation to psychological well-being in Africans relative to Caucasians (white). A total of 102 African and 165 Caucasian school teachers underwent the Stroop Color-Word Conflict test. Circulating levels of von Willebrand factor (VWF) antigen, fibrinogen, and D-dimer were measured before and after the Stroop. Cardiovascular reactivity measures were also obtained. All participants completed the Patient Health Questionnaire-9 and the General Health Questionnaire-28 for the assessment of depressive symptoms and total psychological distress, respectively. After controlling for covariates, resting levels of VWF, fibrinogen, and D-dimer were higher in Africans than in Caucasians (all p-values ≤0.006). Depressive symptoms and psychological distress were not significantly associated with resting coagulation measures. Stress reactivity in VWF (p<0.001) and fibrinogen (p=0.016), but not in D-dimer (p=0.27), were decreased in Africans relative to Caucasians with Africans showing greater reactivity of total peripheral resistance (p=0.017). Depressive symptoms, but not general psychological distress, were associated with greater VWF increase (p=0.029) and greater fibrinogen decrease (p=0.030) in Africans relative to Caucasians. In conclusion, Africans showed greater hypercoagulability at rest but diminished procoagulant reactivity to acute mental stress when compared with Caucasians. Ethnic differences in the vascular adrenergic stress response might partially explain this finding. Depressive symptoms were associated with exaggerated VWF reactivity in Africans relative to Caucasians. The clinical implications of these findings for Africans need further study.

A FUNCTIONAL VARIANT OF HLA-DR1 DELINEATED BY T-LYMPHOCYTE CLONE REACTIVITY, PROTEIN CONFORMATION, AND GENOMIC RESTRICTION SITES

This research characterized a serologically indistinguishable form of HLA-DR1 that: (1) cannot stimulate some DR1-restricted or specific T-lymphocyte clones; (2) displays an unusual electrophoretic pattern on two dimensional gels; and (3) is marked by a polymorphic restriction site of the alpha gene. Inefficient stimulation of some DR1-restricted clones was a property of DR1$\sp{+}$ cells that shared HLA-B14 on the same haplotype and/or were carriers of 21-hydroxylase (21-OH) deficiency. Nonclassical 21-OH deficiency frequently demonstrates genetic linkage with HLA-B14;DR1 haplotypes and associates with duplications of C4B and one 21-OH gene. Cells having both stimulatory (DR1$\sb{\rm n}$) and nonstimulatory (DR1$\sb{\rm x}$) parental haplotypes did not mediate proliferation of these clones. However, heterozygous DR1$\sb{\rm x}$, 2 and DR1$\sb{\rm x}$, 7 cells were efficient stimulators of DR2 and DR7 specific clones, respectively, suggesting that a trans acting factor may modify DR1 alleles or products to yield a dominant DR1$\sb{\rm x}$ phenotype. Incompetent stimulator populations did not secrete an intercellular soluble or contact dependent suppressor factor nor did they express interleukin-2 receptors competing for T-cell growth factors. Two dimensional gel analysis of anti-DR immunoprecipitates revealed, in addition to normal DR$\alpha$ and DR$\beta$ chains, a 50kD species from DR1$\sb{\rm x}$ but not from the majority of DR1$\sb{\rm n}$ or non-DR1 cells. The 50kD structure was stable under reducing conditions in SDS and urea, had antigenic homology with DR, and dissociated after boiling into 34kD and 28kD peptide chains apparently identical with DR$\alpha$ and DR$\beta$ as shown by limited digest peptide maps. N-linked glycosylation and sialation of DRgp50 appeared to be unchanged from normal DR$\alpha$ and DR$\beta$. Bg1II digestion and $DR\alpha$ probing of DR1$\sb{\rm x}$ genomic DNA revealed a 4.5kb fragment while DR1$\sb{\rm n}$ DNA yielded 3.8 and 0.76kb fragments; all restriction sites mapped to the 3$\sp\prime$ untranslated region of $DR\alpha$. Collectively, these data suggest that DRgp50 represents a novel combinatorial association between constitutive chains of DR that may interfere with or compete for normal T cell receptor recognition of DR1 as both an alloantigen and restricting element. Furthermore, extensive chromosomal abnormalities previously mapped to the class III region of B14;DR1 haplotypes may extend into the adjacent class II region with consequent intrusion on immune function. ^

Reactivity of hexanuclear ruthenium metallaprisms towards nucleotides and a DNA decamer

The reactivity of three hexacationic arene ruthenium metallaprisms towards isolated nucleotides and a short DNA strand was investigated using NMR spectroscopy, ESI mass spectrometry, UV/Vis and circular dichroism spectroscopy. The metallaprism built from oxalato-bridging ligands reacts rapidly in the presence of deoxyguanosine monophosphate (dGMP) and deoxyadenosine monophosphate, while the benzoquinonato derivative only reacts with dGMP. On the other hand, the larger metallaprism incorporating naphtoquinonato bridges remains stable in the presence of nucleotides. The reactivity of the three hexacationic metallaprisms with the decameric oligonucleotide d(CGCGATCGCG)2 was also investigated. Analysis of the NMR, MS, UV/Vis and CD data suggests that no adducts are formed between the oligonucleotide and the metallaprisms, but electrostatic interactions, leading to partial unwinding of the double-stranded oligonucleotide, were evidenced

Reactivity to Accelerometer Measurement of Children and Adolescents

PURPOSE: Awareness of being monitored can influence participants' habitual physical activity (PA) behavior. This reactivity effect may threaten the validity of PA assessment. Reports on reactivity when measuring the PA of children and adolescents have been inconsistent. The aim of this study was to investigate whether PA outcomes measured by accelerometer devices differ from measurement day to measurement day and whether the day of the week and the day on which measurement started influence these differences. METHODS: Accelerometer data (counts per minute [cpm]) of children and adolescents (n = 2081) pooled from eight studies in Switzerland with at least 10 h of daily valid recording were investigated for effects of measurement day, day of the week, and start day using mixed linear regression. RESULTS: The first measurement day was the most active day. Counts per minute were significantly higher than on the second to the sixth day, but not on the seventh day. Differences in the age-adjusted means between the first and consecutive days ranged from 23 to 45 cpm (3.6%-7.1%). In preschoolchildren, the differences almost reached 10%. The start day significantly influenced PA outcome measures. CONCLUSIONS: Reactivity to accelerometer measurement of PA is likely to be present to an extent of approximately 5% on the first day and may introduce a relevant bias to accelerometer-based studies. In preschoolchildren, the effects are larger than those in elementary and secondary schoolchildren. As the day of the week and the start day significantly influence PA estimates, researchers should plan for at least one familiarization day in school-age children and randomly assign start days.

Abacavir induced T cell reactivity from drug naïve individuals shares features of allo-immune responses.

Abacavir hypersensitivity is a severe hypersensitivity reaction which occurs exclusively in carriers of the HLA-B*57∶01 allele. In vitro culture of PBMC with abacavir results in the outgrowth of abacavir-reacting CD8+ T cells, which release IFNγ and are cytotoxic. How this immune response is induced and what is recognized by these T cells is still a matter of debate. We analyzed the conditions required to develop an abacavir-dependent T cell response in vitro. The abacavir reactivity was independent of co-stimulatory signals, as neither DC maturation nor release of inflammatory cytokines were observed upon abacavir exposure. Abacavir induced T cells arose in the absence of professional APC and stemmed from naïve and memory compartments. These features are reminiscent of allo-reactivity. Screening for allo-reactivity revealed that about 5% of generated T cell clones (n = 136) from three donors were allo-reactive exclusively to the related HLA-B*58∶01. The addition of peptides which can bind to the HLA-B*57∶01-abacavir complex and to HLA-B*58∶01 during the induction phase increased the proportion of HLA-B*58∶01 allo-reactive T cell clones from 5% to 42%. In conclusion, abacavir can alter the HLA-B*57∶01-peptide complex in a way that mimics an allo-allele ('altered self-allele') and create the potential for robust T cell responses.

An in situ surface electrochemistry approach towards whole-cell studies: the structure and reactivity of a Geobacter sulfurreducens submonolayer on electrified metal/electrolyte interfaces

A direct electron transfer process between bacterial cells of electrogenic species Geobacter sulfurreducens (Gs) and electrified electrode surfaces was studied to exploit the reactivity of Gs submonolayers on gold and silver surfaces. A submonolayer of Gs was prepared and studied to explore specifically the heterogeneous electron transfer properties at the bacteria/electrode interface. In situ microscopic techniques characterised the morphology of the Gs submonolayers under the operating conditions. In addition, complementary in situ spectroscopic techniques that allowed us to access in situ molecular information of the Gs with high surface selectivity and sensitivity were employed. The results provided clear evidence that the outermost cytochrome C in Gs is responsible for the heterogeneous electron transfer, which is in direct contact with the metal electrode. Feasibility of single cell in situ studies under operating conditions was demonstrated where the combination of surface-electrochemical tools at the nano- and micro-scale with microbiological approaches can offer unique opportunities for the emerging field of electro-microbiology to explore processes and interactions between microorganisms and electrical devices.

Probing the Electrocatalytic Oxygen Reduction Reaction Reactivity of Immobilized Multicopper Oxidase CueO

The bioelectrocatalytic (oxygen reduction reaction, ORR) properties of the multicopper oxidase CueO immobilized on gold electrodes were investigated. Macroscopic electrochemical techniques were combined with in situ scanning tunneling microscopy (STM) and surface-enhanced Raman spectroscopy at the ensemble and at the single-molecule level. Self-assembled monolayer of mercaptopropionic acid, cysteamine, and p-aminothiophenol were chosen as redox mediators. The highest ORR activity was observed for the protein attached to amino-terminated adlayers. In situ STM experiments revealed that the presence of oxygen causes distinct structure and electronic changes in the metallic centers of the enzyme, which determine the rate of intramolecular electron transfer and, consequently, affect the rate of electron tunneling through the protein. Complementary Raman spectroscopy experiments provided access for monitoring structural changes in the redox state of the type 1 copper center of the immobilized enzyme during the CueO-catalyzed oxygen reduction cycle. These results unequivocally demonstrate the existence of a direct electronic communication between the electrode substrate and the type 1 copper center.