Harm avoidance is related to mismatch negativity (MMN) amplitude in healthy subjects

peer reviewedEvent-related potential (ERP) studies evidenced that some personality dimensions induced different controlled cognitive attitudes towards the processing of information. However, few data are available on the possible relationships between personality and automatic attention or early sensory processing. In the present study the relationships between the mismatch negativity (MMN) and personality described by the Cloninger model of personality were investigated. Subjects were 32 healthy volunteers. The MMN was recorded with frequent stimuli tones of 1470 Hz, 70 dB and 40 ms duration, and target (20%) tones of 1470 Hz, 70 dB, 80 ms duration. The subjects completed a French version of the 226-item self-questionnaire TCI within the day following psychophysiological recording. The results showed that the HA dimension was negatively correlated with the MMN amplitude. The association was more present among women than men. No significant relationship existed between the other dimensions of personality and either the MMN amplitude or latency. These findings suggest that the MMN is related to the behavioral inhibition system (BIS), a fact which is consistent with clinical studies conducted on schizophrenia and anxiety disorders. In conclusion, this study suggests that personality dimensions induce different automatic attitudes towards the processing of information. (C) 2002 Published by Elsevier Science Ltd

Association between serum interleukin-6 and serum 3,5,3'-triiodothyronine in nonthyroidal illness

Increased serum concentrations of FFA, bilirubin, and carboxyl-methyl-propyl-furanpropionic acid, accumulating in chronic renal failure in direct relationship with serum creatinine, have all been implicated in the pathogenesis of the low T3 syndrome during illness. Cytokines may also be involved in the sick euthyroid syndrome. In contrast to interleukin-1 (IL-1) and tumor necrosis factor-alpha, IL-6 is usually detectable in serum during illness and acts as a systemic hormone. We studied the association between serum T3 and IL-6 in consecutive hospital admissions with a wide variety of medical conditions. Patients were divided into group A (T3, > or = 1.30 nmol/L; T4, > or = 75 nmol/L; n = 41), group B (T3, or = 75 nmol/L; n = 46), and group C (T3, <1.30 nmol/L; T4, <75 nmol/L; n = 13). Serum IL-6 levels in groups C and B were higher than those in group A (median values 59, 39, and 9 U/mL, respectively; P <0.01). Serum creatinine and bilirubin/albumin ratios were similar in the three groups, but the FFA/albumin ratio in group C was higher than in group A (P <0.05). When all patients were analyzed together, serum T3 was negatively correlated to serum IL-6 (r = -0.56; P <0.001), bilirubin/albumin ratio (r = -0.29; P = 0.004), and FFA/albumin ratio (r = -0.21; P = 0.03), but not with creatinine (r = -0.16; P = 0.11). Stepwise multiple regression resulted in the following equation: serum T3 = 2.13-0.18ln(IL-6)-0.15ln(creatinine)-0.094ln(bilirubin /albumin) (r = 0.61). The variability in serum T3 was accounted for 28% by ln(IL-6), 5% by ln(creatinine), and 4% by ln(bilirubin/albumin). FFA/albumin did not contribute in this respect. We conclude that the low T3 syndrome in nonthyroidial illness is associated with high serum IL-6 levels. However, even when IL-6 is assumed to play a causative role, the variation of serum T3 in NTI-patients remains largely unexplaine

The role of cytokines in the lipopolysaccharide-induced sick euthyroid syndrome in mice

To evaluate the role of cytokines in the sick euthyroid syndrome, we tried to establish an animal model of non-thyroidal illness in mice by the administration of a sub-lethal dose of bacterial endotoxin (lipopolysaccharide; LPS) which induces a variety of cytokines, including tumour necrosis factor (TNF alpha), interleukin-1 (IL-1 alpha), interleukin-6 (IL-6) and interferon-gamma (IFN gamma). When compared with pair-fed controls, a single dose of LPS resulted in (a) systemic illness, (b) induction of TNF alpha and IL-6 and (c) a decrease of liver 5'-deiodinase mRNA from 4 h onwards followed by a decrease of serum tri-iodothyronine (T3) and thyroxine (T4) at 8 h and of serum free T3 (fT3) and free T4 (fT4) at 24 h; serum TSH remained unchanged. We then studied whether a single dose or a combination of IL-1 alpha, TNF alpha, IL-6 or IFN gamma could induce the sick euthyroid syndrome in mice, again using pair-fed controls. None of the cytokines except IL-1 alpha caused systemic illness, and IL-1 alpha was the only cytokine that decreased liver 5'-deiodinase mRNA transiently. IL-1 alpha, TNF alpha or IL-6 did not decrease serum T3, T4 and TSH, but administration of IFN gamma decreased serum T4, T3 and fT3 in a dose-dependent manner without changes in serum TSH. Administration of all four cytokines together had no synergistic effects; observed changes were of a smaller magnitude than after LPS. The following conclusions were reached.(ABSTRACT TRUNCATED AT 250 WORDS

Hyper and hypothyroidism change the expression and diurnal variation of thyroid hormone receptor isoforms in rat liver without major changes in their zonal distribution

We investigated the effect of hypothyroidism or hyperthyroidism on mRNA and protein expression, diurnal variation and zonal distribution of thyroid hormone receptor (TR) isoforms TRalpha1 TRalpha2 and TRbeta1 in rat liver. Hypothyroidism results in increased isoform mRNA and protein expression whereas hyperthyroidism shows a decreased TRalpha1 and TRalpha2 mRNA and protein expression. During hyperthyroidism no change is seen in TRbeta1 mRNA, but TRbeta1 protein is upregulated in the light period and downregulated in the dark period. Diurnal changes (measured at 13:30 and 19:30 h) in the TR isoform proteins are abolished in hypothyroidism and hyperthyroidism, with the exception of a reversal in diurnal changes of TRbeta1 in hyperthyroidism. Zonal distribution of the isoforms is not affected by hypo- or hyperthyroidism. We therefore conclude that thyroid hormone influences both the levels and the diurnal expression of its receptor isoforms but not the zonal distribution. (C) 2004 Elsevier Ireland Ltd. All rights reserve

Contribution of interleukin-12 to the pathogenesis of non-thyroidal illness

Changes in both central and peripheral thyroid hormone (TH) metabolism occur during illness. These changes, known collectively as non-thyroidal illness, are apparently mediated by the proinflammatory cytokines IL-6,TNFalpha and IFNgamma. IL-12 is involved in regulation of IFNgamma and TNFalpha. The aim of this study was to evaluate the role of IL-12 in TH metabolism during illness. We studied TH metabolism both centrally (in the pituitary) and peripherally (in the liver) in IL-12 knock-out (IL-12(-/-)) and wild type (WT) mice during illness induced by administration of bacterial endotoxin (LPS). LPS induced a similar decrease in serum T-3, T-4 and liver 5'-DI mRNA expression in IL-12(-/-) and WT mice with the exception of a smaller reduction of serum T4 in IL-12(-/-) mice. In the pituitary, the LPS-induced decline in 5'-DI activity in WT mice was not observed in IL-12(-/-) mice (p <0.001), whereas the decrease in DII activity tended to be smaller in IL-12(-/-) mice (p = 0.066). The lower decrease in pituitary activity of both DI and DII in IL-12(-/-) mice is possibly related to the lower LPS-induced T4 decrease. In conclusion, IL-12 is involved in the central regulation of the HPT axis during illness but not in the peripheral regulatio

Tuning microfluidic flow by pulsed light oscillating spiropyran-basedpolymer hydrogel valves

A method for microfluidic flow control based upon polymer hydrogel valves with rapid and reversible actuation properties is described. The platform allows for contactless optical flow control based upon pulsing light, resulting in a forced oscillating and control over the valve through photo-isomerisation of a spiropyran derivative, co-polymerised within an N-isopropylacrylamide (NIPAm) hydrogel. Application of pulsed light (450 nm) to the valves allows the valves to be held at an intermediate position for extended periods of time. Varying the extent of pulsing of the light source enables the flow rate to be regulated within a microfluidic flow rate range of 0–27 μL/min. Due to the pulsed light, a small period change in the flow rate is observed that corresponds to the pulse sequence as a corresponding oscillation in the hydrogel valves

Molecular design of light-responsive hydrogels, for in situ generation of fast and reversible valves for microfluidic applications

Reversible light-responsive hydrogel valves with response characteristics compatible for microfluidics have been obtained by optimization of molecular design of spiropyran photoswitches and gel composition. Self-protonating gel formulations were exploited, wherein acrylic acid was copolymerized in the hydrogel network as an internal proton donor, to achieve a swollen state of the hydrogel in water at neutral pH. Light-responsive properties were endowed upon the hydrogels by copolymerization of spiropyran chromophores, using electron withdrawing and donating groups to tune the gel-swelling and shrinkage behavior. In all cases, the shrinkage was determined by the water diffusion rate, while for the swelling the isomerization kinetics is the rate-determining step. For one hydrogel, reversible and reproducible volume changes were observed. Finally, gel-valves integrated within microfluidic channels were fabricated, allowing reversible and repeatable operation, with opening and closing of the valve in minutes

Diurnal variation in rat liver thyroid hormone receptor (TR)-alpha messenger ribonucleic acid (mRNA) is dependent on the biological clock in the suprachiasmatic nucleus, whereas diurnal variation of TR beta 1 mRNA is modified by food intake

Previous studies have shown a diurnal variation of certain isoforms of thyroid hormone receptors (TR) in rat liver. The genesis of these diurnal changes is still unknown. To clarify whether the biological clock, located in the hypothalamic suprachiasmatic nucleus (SCN), is involved, we made selective SCN lesions. Rats with an SCN lesion lost their circadian rhythm of plasma corticosterone and TSH when compared with intact animals. TRalpha1 and TRalpha2 mRNA expression of control rats was higher in the light period than in the dark period; changes that were abolished in the rats with SCN lesions. In contrast, liver TRbeta1 mRNA of intact rats showed a diurnal variation that failed to reach statistical significance. To evaluate whether these effects could be explained indirectly by the disappearance of rhythmic feeding behavior in rats with SCN lesions, we performed a second experiment in which otherwise intact animals were subjected to a regular feeding (RF) schedule, with one meal every 4 h. When compared with rats with free access to food, RF only affected TRbeta1 mRNA expression and had no effect on the diurnal changes in TRalpha1 and TRalpha2. We conclude that liver TRbeta1 expression is most clearly affected by food intake. Diurnal changes in liver TRalpha1 and TRalpha2 are controlled by the biological clock in the SCN but not via changes in the daily rhythm of food intake. The findings may have physiological relevance for diurnal variation of T-3-dependent gene expression, which is supported by a diurnal variation in the expression of the 5'-deiodinase gen