Episodic thyrotropin (TSH) and prolactin (PRL) secretion during aging in postmenopausal women.

While aging is known to decrease episodic thyrotropin (TSH) secretion in men, no detailed information is available as to age-related alterations in the TSH and prolactin (PRL) release patterns in postmenopausal women (PMW). Accordingly, we compared the TSH and prolactin (PRL) secretory profiles of 6 euthyroid younger PMW (mean age: 53.0 years) with those of 7 euthyroid older PMW (mean age: 80.4 years). In all PMW, blood samples were obtained at 10 minute intervals for 10 hours for serial determinations of TSH and PRL by RIA. While thyroxine (T4) serum concentrations were not different in younger from older PMW, triiodothyronine (T3) levels markedly (p less than 0.05) decreased in older PMW. In both younger and older PMW, TSH and PRL were secreted episodically (by Cluster pulse algorithm), with considerable inter-individual variabilities in either study group. TSH and PRL pulse attributes (interpulse intervals, frequencies, amplitudes) were comparable in younger and older PMW, although a tendency of mean TSH to increase (p = 0.18) was noted for older PMW. Mean TSH and PRL serum concentrations were positively (r = 0.94, p less than 0.01) correlated in older, whereas not in younger PMW. These observations demonstrate that the pulse characteristics of episodic TSH and PRL secretion are preserved in PMW even of old age. However, in view of markedly decreased circulating T3 concentrations and of no substantial change in the TSH pulsatile secretion in older PMW, the negative feedback on the hypothalamic-pituitary unit may be impaired in elderly women.     

Distorted tetrahedral nickel-nitrosyl complexes: spectroscopic characterization and electronic structure

The linear nickel-nitrosyl complex [Ni(NO)(L3)] supported by a highly hindered tridentate nitrogen-based ligand, hydrotris(3-tertiary butyl-5-isopropyl-1-pyrazolyl)borate (denoted as L3), was prepared by the reaction of the potassium salt of the ligand with the nickel-nitrosyl precursor [Ni(NO)(Br)(PPh ₃ ) ₂ ]. The obtained nitrosyl complexes as well as the corresponding chlorido complexes [Ni(NO)(Cl)(PPh ₃ ) ₂ ] and [Ni(Cl)(L3)] were characterized by X-ray crystallography and different spectroscopic methods including IR/far-IR, UV–Vis, NMR, and multi-edge X-ray absorption spectroscopy at the Ni K-, Ni L-, Cl K-, and P K-edges. For comparative electronic structure analysis we also performed DFT calculations to further elucidate the electronic structure of [Ni(NO)(L3)]. These results provide the nickel oxidation state and the character of the Ni-NO bond. The complex [Ni(NO)(L3)] is best described as [Ni ^II (NO ^– )(L3)], and the spectroscopic results indicate that the phosphane complexes have a similar [Ni ^II (NO ^– )(X)(PPh ₃ ) ₂ ] ground state.     

Photoaffinity labeling of the nucleotide binding site of actin

Rabbit skeletal muscle actin was photoaffinity-labeled by the nucleotide analogue 8-azidoadenosine 5'-triphosphate. In both G-actin and F-actin about 25% covalent incorporation was achieved. The labeled actins were digested with cyanogen bromide, and the labeled peptides were isolated and sequenced. In F-actin the label was bound primarily to Lys-336, while in G-actin the label was bound to Lys-336 or to Trp-356. The results indicate that the nucleotide binding site is near the phalloidin binding site of actin [Vanderkerckhove, J., Deboben, A., Nassal, M., & Wieland, T. (1985) EMBO J. 4, 2815-2818]. The binding of the azido group to Trp-356 in G-actin but not in F-actin may indicate that a change in the conformation of actin occurs in this region.     

A radical solution for the biosynthesis of the H-cluster of hydrogenase

Fe-only or FeFe hydrogenases, as they have more recently been termed, possess a uniquely organometallic enzyme active site, termed the H-cluster, where the electronic properties of an iron-sulfur cluster are tuned with distinctly non-biological ligands, carbon monoxide and cyanide. Recently, it was discovered that radical S-adenosylmethionine enzymes were involved in active hydrogenase expression. In the current work, we present a mechanistic scheme for hydrogenase H-cluster biosynthesis in which both carbon monoxide and cyanide ligands can be derived from the decomposition of a glycine radical. The ideas presented have broader implications in the context of the prebiotic origin of amino acids.     

Exploring new frontiers of nitrogenase structure and mechanism

The mechanism of the complex enzyme nitrogenase has long been one of the most challenging problems in bioinorganic chemistry. The complexity of the metal centers of nitrogenase has stretched the boundaries of biochemical, physical and computational tools for providing insights into its structure and chemical function. Recently, there have been several key advances in crystallography and spectroscopy that have impacted the way the nitrogenase mechanism is approached. These advances have opened new frontiers in nitrogenase research, which has started to reveal novel details about the molecular structure, substrate binding and reduction. Here, we discuss these recent advances and their implications on the future of nitrogenase research.     

Agreement among Healthcare Professionals in Ten European Countries in Diagnosing Case-Vignettes of Surgical-Site Infections

Objective

Although surgical-site infection (SSI) rates are advocated as a major evaluation criterion, the reproducibility of SSI diagnosis is unknown. We assessed agreement in diagnosing SSI among specialists involved in SSI surveillance in Europe.

Methods

Twelve case-vignettes based on suspected SSI were submitted to 100 infection-control physicians (ICPs) and 86 surgeons in 10 European countries. Each participant scored eight randomly-assigned case-vignettes on a secure online relational database. The intra-class correlation coefficient (ICC) was used to assess agreement for SSI diagnosis on a 7-point Likert scale and the kappa coefficient to assess agreement for SSI depth on a three-point scale.

Results

Intra-specialty agreement for SSI diagnosis ranged across countries and specialties from 0.00 (95%CI, 0.00–0.35) to 0.65 (0.45–0.82). Inter-specialty agreement varied from 0.04 (0.00–0.62) in to 0.55 (0.37–0.74) in Germany. For all countries pooled, intra-specialty agreement was poor for surgeons (0.24, 0.14–0.42) and good for ICPs (0.41, 0.28–0.61). Reading SSI definitions improved agreement among ICPs (0.57) but not surgeons (0.09). Intra-specialty agreement for SSI depth ranged across countries and specialties from 0.05 (0.00–0.10) to 0.50 (0.45–0.55) and was not improved by reading SSI definition.

Conclusion

Among ICPs and surgeons evaluating case-vignettes of suspected SSI, considerable disagreement occurred regarding the diagnosis, with variations across specialties and countries.     

Multivariate Analysis of Dopaminergic Gene Variants as Risk Factors of Heroin Dependence

Background

Heroin dependence is a debilitating psychiatric disorder with complex inheritance. Since the dopaminergic system has a key role in rewarding mechanism of the brain, which is directly or indirectly targeted by most drugs of abuse, we focus on the effects and interactions among dopaminergic gene variants.

Objective

To study the potential association between allelic variants of dopamine D2 receptor (DRD2), ANKK1 (ankyrin repeat and kinase domain containing 1), dopamine D4 receptor (DRD4), catechol-O-methyl transferase (COMT) and dopamine transporter (SLC6A3) genes and heroin dependence in Hungarian patients.

Methods

303 heroin dependent subjects and 555 healthy controls were genotyped for 7 single nucleotide polymorphisms (SNPs) rs4680 of the COMT gene; rs1079597 and rs1800498 of the DRD2 gene; rs1800497 of the ANKK1 gene; rs1800955, rs936462 and rs747302 of the DRD4 gene. Four variable number of tandem repeats (VNTRs) were also genotyped: 120 bp duplication and 48 bp VNTR in exon 3 of DRD4 and 40 bp VNTR and intron 8 VNTR of SLC6A3. We also perform a multivariate analysis of associations using Bayesian networks in Bayesian multilevel analysis (BN-BMLA).

Findings and conclusions

In single marker analysis the TaqIA (rs1800497) and TaqIB (rs1079597) variants were associated with heroin dependence. Moreover, –521 C/T SNP (rs1800955) of the DRD4 gene showed nominal association with a possible protective effect of the C allele. After applying the Bonferroni correction TaqIB was still significant suggesting that the minor (A) allele of the TaqIB SNP is a risk component in the genetic background of heroin dependence. The findings of the additional multiple marker analysis are consistent with the results of the single marker analysis, but this method was able to reveal an indirect effect of a promoter polymorphism (rs936462) of the DRD4 gene and this effect is mediated through the –521 C/T (rs1800955) polymorphism in the promoter.     

PP13, maternal ABO blood groups and the risk assessment of pregnancy complications

Background

Placental Protein 13 (PP13), an early biomarker of preeclampsia, is a placenta-specific galectin that binds beta-galactosides, building-blocks of ABO blood-group antigens, possibly affecting its bioavailability in blood.

Methods and Findings

We studied PP13-binding to erythrocytes, maternal blood-group effect on serum PP13 and its performance as a predictor of preeclampsia and intrauterine growth restriction (IUGR). Datasets of maternal serum PP13 in Caucasian (n = 1078) and Hispanic (n = 242) women were analyzed according to blood groups. In vivo, in vitro and in silico PP13-binding to ABO blood-group antigens and erythrocytes were studied by PP13-immunostainings of placental tissue-microarrays, flow-cytometry of erythrocyte-bound PP13, and model-building of PP13 - blood-group H antigen complex, respectively. Women with blood group AB had the lowest serum PP13 in the first trimester, while those with blood group B had the highest PP13 throughout pregnancy. In accordance, PP13-binding was the strongest to blood-group AB erythrocytes and weakest to blood-group B erythrocytes. PP13-staining of maternal and fetal erythrocytes was revealed, and a plausible molecular model of PP13 complexed with blood-group H antigen was built. Adjustment of PP13 MoMs to maternal ABO blood group improved the prediction accuracy of first trimester maternal serum PP13 MoMs for preeclampsia and IUGR.

Conclusions

ABO blood group can alter PP13-bioavailability in blood, and it may also be a key determinant for other lectins'' bioavailability in the circulation. The adjustment of PP13 MoMs to ABO blood group improves the predictive accuracy of this test.     

Reduction of Nitrite and Nitrate to Ammonium on Pyrite

An important constraint on the formation of the building blocks of life in the Hadean is the availability of small, activated compounds such as ammonia (NH(3)) relative to its inert dinitrogen source. Iron-sulfur particles and/or mineral surfaces have been implicated to provide the catalytic active sites for the reduction of dinitrogen. Here we provide a combined kinetic, spectroscopic, and computational modeling study for an alternative source of ammonia from water soluble nitrogen oxide ions. The adsorption of aqueous nitrite (NO (2) (-) ) and nitrate (NO (3) (-) ) on pyrite (FeS(2)) and subsequent reduction chemistry to ammonia was investigated at 22°C, 70°C, and 120°C. Batch geochemical and in situ Attenuated Total Reflection - Fourier Transform Infrared (ATR-FTIR) spectroscopy experiments were used to determine the reduction kinetics to NH(3) and to elucidate the identity of the surface complexes, respectively, during the reaction chemistry of NO (2) (-) and NO (3) (-) . Density functional theory (DFT) calculations aided the interpretation of the vibrational data for a representative set of surface species. Under the experimental conditions used in this study, we detected the adsorption of nitric oxide (NO) intermediate on the pyrite surface. NH(3) production from NO (2) (-) occurred at 70 and 120°C and from NO (3) (-) occurred only at 120°C.