Novel experimental setup for megahertz X-ray diffraction in a diamond anvil cell at the High Energy Density (HED) instrument of the European X-ray Free-Electron Laser (EuXFEL)

The high-precision X-ray diffraction setup for work with diamond anvil cells (DACs) in interaction chamber 2 (IC2) of the High Energy Density instrument of the European X-ray Free-Electron Laser is described. This includes beamline optics, sample positioning and detector systems located in the multipurpose vacuum chamber. Concepts for pump-probe X-ray diffraction experiments in the DAC are described and their implementation demonstrated during the First User Community Assisted Commissioning experiment. X-ray heating and diffraction of Bi under pressure, obtained using 20 fs X-ray pulses at 17.8 keV and 2.2 MHz repetition, is illustrated through splitting of diffraction peaks, and interpreted employing finite element modeling of the sample chamber in the DAC.

Pressure dependence of Ce valence in CeRhIn5

We have studied the Ce valence as a function of pressure in CeRhIn₅ at 300 K and at 22 K using x-ray absorption spectroscopy in partial fluorescent yield mode. At room temperature, we found no detectable change in Ce valence greater than 0.01 up to a pressure of 5.5 GPa. At 22 K, the valence remains robust against pressure below 6 GPa, in contrast to the predicted valence crossover at P  =  2.35 GPa. This work yields an upper limit for the change in Ce-valence and suggests that the critical valence fluctuation scenario, in its current form, is unlikely.

Aortic stiffness and left ventricular function in patients with differentiated thyroid cancer

OBJECTIVE

The aim of this study was to investigate aortic stiffness and left ventricular (LV) systolic and diastolic function in patients with differentiated thyroid cancer (DTC) on thyroxine (L-T4) therapy and after L-T4 withdrawal to assess the cardiovascular impact of long-term subclinical hyperthyroidism and short-term overt hypothyroidism.

METHODS

Twenty-four patients who had had total thyroidectomy and radioiodine ablation for differentiated thyroid cancer were studied on two occasions: on TSH suppressive L-T4 therapy (sTSH 0.24 ± 0.11 mU/L), and 4 weeks after L-T4 withdrawal (sTSH 89.82 ± 29.36 mU/L). Echocardiography was performed and thyroid function, serum thyroglobulin, lipid parameters, homocystine, C-reactive protein, fibrinogen and von Willebrand factor activity (vWF) were measured. Twenty-two healthy volunteers matched for age and sex served as euthyroid controls.

RESULTS

Aortic stiffness was increased both in hypothyroidism (6.04 ± 2.88 cm(2)/dyn/10(3), p < 0.05) and subclinical hyperthyroidism (9.27 ± 4.81 cm(2)/dyn/10(3), p < 0.05) vs. controls (3.92 ± 1.84 cm(2)/dyn/10(3)). Subclinical hyperthyroidism had a more marked effect (p < 0.05). LV dimensions and ejection fractions were similar before and after L-T4 withdrawal. The E'/A' was higher in euthyroid controls (1.34 ± 1.02) as compared to both subclinical hyperthyroidism (1.0 ± 0.14, p < 0.05) and overt hypothyroidism (1.13 ± 0.98, p < 0.05). Change of aortic stiffness correlated with change of free-thyroxine (fT4), vWF and fibrinogen levels in a positive manner.

CONCLUSION

Long-term thyrotropin-suppression therapy has continuous adverse effects on the arterial wall. The degree of TSH suppression in patients with DTC should be kept at the possible minimum, based on individually determined potential benefits and risks of treatment, especially in patients with cardiovascular co-morbidities.

Evaluation of the thyroid function of healthy pregnant women by five different hormone assays

A normal function of the thyroid gland during pregnancy is essential. Any change can affect both the pregnant woman and the fetus. Thyroid hormones play a crucial role in the brain development of the fetus, thus proper maternal free thyroid hormone levels are important especially during the first trimester. We compared the free thyroid hormone levels FT3 and FT4 in forty pregnant women with no thyroidal disease by five different assays available on the market. The blood samples were collected between the 8th and 22nd weeks of pregnancy. The correlation coefficient "r" between different assays was 0.908-0.975 for TSH, 0.676-0.892 for FT4 and 0.480-0.789 for FT3. These data show that the inter-assay results varied widely in the studied population. One reasonable explanation may be that during pregnancy the serum levels of the thyroid hormone binding proteins are altered and "free" hormone measurements by immunoassays are influenced by these alterations. Thus, the results may show higher or lower thyroid hormone values depending upon the assay used. Therefore, it is strongly suggested that every laboratory should establish its own pregnant reference ranges for the tests used for the evaluation of thyroid function, based on values of the population served.

The epidemiology of hypertension and its associated risk factors in the city of Debrecen, Hungary

The purpose of this work was to estimate the prevalence of hypertension and cardiovascular risk factors and its association with sociodemographic, behavioural and lifestyle characteristics among the adult population of the city of Debrecen, Hungary.A cross-sectional study was conducted in 1996. Amongst 21 800 inhabitants aged 30-65 y risk screening for cardiovascular disease (CVD) was estimated by a questionnaire that included sociodemographic, lifestyle characteristics, family history of CVD and results of self-reported data of body weight, height and blood pressure. Of the total of 19 961 surveyed sample, 37.02% were considered to be hypertensive, 53.73% were overweight, 32.18% were current smokers and 58.85% were physically inactive. Hypertensives were older than normotensives (50.81+/-9.01 vs 44.78+/-8.97 y, P<0.001). The prevalence of various risk factors amongst hypertensives as compared to normotensives were overweight (68.49 vs 45.06%, P<0.0001), current smoking (28.38 vs 34.41%, P<0.0001), physical inactivity (64.78 vs 55.36%, P<0.001), and high alcohol consumption (1.91 vs 1.06%, P<0.01). Of the hypertensives 37.11% were on drug therapy. Of those on therapy, only 17.03% had normal blood pressure. Being overweight and having low physical activity was positively associated with hypertension (OR=2.25, CI=2.11-2.40) and (OR=1.26, CI=1.15-1.38). Manual work, a family history of CVD, low education, and the male gender were also associated with hypertension and more CVD risk factors. These findings illustrate a very high prevalence of hypertension and CVD risk factors in Debrecen, indicating the importance of the need for more effective prevention programmes and control of hypertension in Hungary.

[Epidemiology of hypertension in adolescence and factors influencing blood pressure]

The authors summarize the determining and influencing factors of adolescent hypertension. An overview of the definition and prevalence of hypertension in adolescence is given and the predictive role of the adolescent hypertension on the incidence of adult cardiovascular diseases is pointed out. According to the previous literature data, adult hypertension is more frequent in those people who have had hypertension in their adolescence. There are no widely used, population-based nomograms of adolescent hypertensives available. According to the opinion of the authors, a population-based hypertension screening program would help in delineating the factors influencing adolescent blood pressure, and the most frequent risk factors for hypertension in Hungary. With the follow-up and appropriate treatment of the hypertensives the reduction of target-organ damages may be possible.

Prevalence of cardiovascular risk factors of the smokers and non-smokers in the city of Debrecen, Hungary

The aim of our study was to compare the major cardiovascular disease (CVD) risk factors of smokers and non-smokers. Risk screening of CVD was estimated by a questionnaire, via interview. Random samples of 20 000 inhabitants of Debrecen, Hungary, aged 30-65 y, took part in the study. 19 922 questionnaires were considered appropriate for further evaluation. 32.2% of the participants (n=6410) were smokers, whose data were compared to those of the 68.8% of non-smokers (n=13 512). There were more male smokers than female (39.3% vs 27.7%), (P<0.001). 36.5% of males and 58.9% of females had not previously smoked regularly (P<0.001). 24.2% of males and only 13.3% of females were able to stop smoking (P<0.001). 8.7% of the participants smoked more than 20 cigarettes per day (14.8% of males, 5.0% of females), (P<0.001). Smokers were younger, with a mean age of 43.4 y vs 47.1 y for non-smokers (P<0.01). The ex-smokers and non-smokers had a higher body mass index than light, moderate and heavy smokers (26. 75+/-4.1 kg/m2 and 26.09+/-4.3 kg/m2 vs 24.87+/-3.9 kg/m2 and 24. 89+/-4.2 kg/m2 and 25.32+/-4.3 kg/m2, respectively), (P<0.001). The results of the last measured blood pressures did not differ between the two groups. 94.8% of smokers and 93.6% of non-smokers did not perform any regular leisure time exercises (P<0.01). 39.8% of smokers regularly ate fatty food, in comparison to 28.0% of non-smokers (P<0.001). 30.6% of smokers vs 28.6% of non-smokers were factory workers while 69.4% of smokers vs 71.4% of non-smokers did sedentary jobs (P<0.001). 2.3% of smokers vs 0.9% of non-smokers admitted regular consumption of alcohol (P<0.001). Amongst the parents and brothers/sisters of smokers the prevalence of heart attack was higher 19.7% vs 18.7%, than for those of non-smokers (P<0. 05). We observed an accumulation of cardiovascular risk factors in the case of smokers, which indicates the higher susceptibility of smokers to CVD.

Interference of S-alkyl derivatives of glutathione with brain ionotropic glutamate receptors

The effects of glutathione, glutathione sulfonate and S-alkyl derivatives of glutathione on the binding of glutamate and selective ligands of ionotropic N-methyl-D-aspartate (NMDA) and non-NMDA receptors were studied with mouse synaptic membranes. The effects of glutathione and its analogues on 45Ca2+ influx were also estimated in cultured rat cerebellar granule cells. Reduced and oxidized glutathione, glutathione sulfonate, S-methyl-, -ethyl-, -propyl-, -butyl- and -pentylglutathione inhibited the Na+-independent binding of L-[3H]glutamate. They strongly inhibited also the binding of (S)-2-amino-3-hydroxy-5-[3H]methyl-4-isoxazolepropionate [3H]AMPA (IC50 values: 0.8-15.9 microM). S-Alkylation of glutathione rendered the derivatives unable to inhibit [3H]kainate binding. The NMDA-sensitive binding of L-[3H]glutamate and the binding of 3-[(R)-2-carboxypiperazin-4-yl][1,2-(3)H]propyl-1-phosphonate ([3H]CPP, a competitive antagonist at NMDA sites) were inhibited by the peptides at micromolar concentrations. The strychnine-insensitive binding of the NMDA coagonist [3H]glycine was attenuated only by oxidized glutathione and glutathione sulfonate. All peptides slightly enhanced the use-dependent binding of [3H]dizocilpine (MK-801) to the NMDA-gated ionophores. This effect was additive with the effect of glycine but not with that of saturating concentrations of glutamate or glutamate plus glycine. The glutamate- and NMDA-evoked influx of 45Ca2+ into cerebellar granule cells was inhibited by the S-alkyl derivatives of glutathione. We conclude that besides glutathione the endogenous S-methylglutathione and glutathione sulfonate and the synthetic S-alkyl derivatives of glutathione act as ligands of the AMPA and NMDA receptors. In the NMDA receptor-ionophore these glutathione analogues bind preferably to the glutamate recognition site via their gamma-glutamyl moieties.

Ligand binding to porcine ionotropic glutamate receptors with chemically modified arginyl residues

The involvement of arginyl residues in the binding of ligands to different ionotropic glutamate receptors, to the modulatory glycine site in the N-methyl-D-aspartate (NMDA) receptor and to the NMDA-governed ionophore was assessed with porcine cortical synaptic membranes. The arginyl residues were covalently modified with phenylglyoxal. The binding and protection experiments showed that arginine residue(s) are directly involved in the binding of ligands to the agonist sites of all ionotropic glutamate receptors and to the modulatory glycine site but not to the ion channel in the NMDA receptor complex.

Glutathione is an endogenous ligand of rat brain N-methyl-D-aspartate (NMDA) and 2-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptors

A study was made of the effects of reduced (GSH) and oxidized (GSSG) glutathione on the Na(+)-independent and N-methyl-D-aspartate (NMDA) displaceable bindings of glutamate, on the binding of kainate, 2-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA), and ligand of the brain NMDA receptor-ionophore complex: glycine, dizocilpine (MK-801) and (+/-)-3-(2-carboxypiperazin-4-yl)propyl-1-phosphonate (CPP). GSH and GSSG strongly inhibited the binding of glutamate, CPP and AMPA, kainate and glycine binding being less affected. Both peptides enhanced the binding of dizocilpine in a time- and concentration-dependent manner. This activatory effect was not additive to that of saturating concentrations of glutamate or glutamate plus glycine. The activation of dizocilpine binding by GSH and GSSG was prevented by the competitive NMDA and glycine antagonists DL-2-amino-5-phosphonovalerate and 7-chlorokynurenate. GSH and GSSG may be endogenous ligands of AMPA and NMDA receptors, binding preferably to the glutamate recognition site via their gamma-glutamyl moieties. In addition to this, at millimolar concentrations they may regulate the redox state of the NMDA receptor-ionophore complex.

Role of histidyl residues in the binding of ligands to the porcine N-methyl-D-aspartate receptor

Possible involvement of histidyl residues in the binding of ligands to ionotropic glutamate receptors and to modulatory sites on the N-methyl-D-aspartate (NMDA) receptor was assessed in porcine cortical synaptic plasma membranes after covalent modification with diethyl pyrocarbonate (DEPC). Binding of [3H]glutamate to the NMDA sites was enhanced but to the 2-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) and kainate receptors unaffected by 1 and 5 mM DEPC. Binding of 3-[(R)-carboxypiperazin-4-yl]-[1,2-(3)H]propyl-1-phosphonate ([3H]CPP) was reduced in a dose-dependent manner by DEPC and the activation of binding by 1-hydroxy-3-amino-2-pyrrolidone (HA-966) blocked by 10 mM DEPC. DEPC reduced the strychnine-insensitive binding of [3H]glycine and the glycine- and glutamate-activated binding of [3H]dizocilpine. Protection experiments indicated that histidyl residues are directly involved in the binding of glycine (but not HA-966) and allosterically modulate the binding of glutamate, CPP and dizocilpine. The results corroborate the existence of agonist- and antagonist-preferring sites or conformational states of the NMDA receptors.