Effect of Sonic Application of Self-etch Adhesives on Bonding Fiber Posts to Root Canal Dentin.

PURPOSE: To evaluate the effect of sonic application of 5 different self-etch adhesives on the push-out bond strength of fiber posts in root canals. MATERIALS AND METHODS: In a preliminary test, 24 teeth were treated with manual and sonically assisted bonding, then a composite cylinder was built up to test the shear bond strength as a proof of principle. In the main test, 120 root canals were endodontically prepared and divided into 10 groups: 5 self-etch adhesives (Futurabond DC, Futurabond M, Futurabond U, Optibond XTR, Universalbond), each applied under manual and sonic application modes. After insertion of the fiber posts using the specific adhesive and a dual-curing composite, the teeth were sectioned and the push-out test was performed. The specimens were analyzed by light and scanning electron microscopy. Statistical analysis was performed using the Shapiro-Wilk test, one-way ANOVA and the Tamhane test. RESULTS: Sonic application of self-etch adhesive systems did not increase the bond strength of fiber posts in root canals. In general, the bond strength decreased from the coronal to the apical part of the root canal, irrespective of the applied method. The best post retention was achieved with Futurabond U and Optibond XTR. CONCLUSION: Sonic application of self-etch adhesives did not improve the fiber post retention in the root canal and can therefore not be recommended. Nevertheless, sonic application of etch-and-rinse adhesives can increase the bond strength to coronal dentin.

Regulation of the human endogenous retroviral Syncytin-1 and cell-cell fusion by the nuclear hormone receptors PPARγ/RXRα in placentogenesis.

Cytotrophoblast (CT) cell fusion into a syncytiotrophoblast is obligatory for placentation and mediated by the human endogenous retrovirus (HERV)-W envelope gene Syncytin-1. Abnormal placentation is associated with preeclampsia (PE), HELLP and intrauterine growth restriction (IUGR). In placentogenesis, the MAP-kinase p38α regulates PPARγ/RXRα signaling and target genes, like leptin, resistin, ABCG2, and hCG. The aim of this study was to analyze PPARγ/RXRα signaling and target gene regulation using primary CT cultures, the trophoblastic cell line BeWo and placental tissues from patients with normal and abnormal placentation. CT from four different human control placentae and BeWo cells demonstrated that Syncytin-1, other signaling members and CT cell fusions were regulated with PPARγ/RXRα activators troglitazone and 9-cis retinoic acid, via protein kinase A and p38α inhibition. Significant discordant regulations between CTs and BeWo were found. Two PPARγ/RXRα-response-elements from upstream regulatory elements and the 5'LTR of HERV-W were confirmed with DNA-protein binding assays using nuclear extracts and recombinant PPARγ/RXRα proteins. These promoter elements were validated with luciferase assays in the presence of PPARγ/RXRα modulators. Furthermore, troglitazone or 9-cis retinoic acid treatment of siRNA-PPARγ and siRNA-RXRα transfected BeWo cells proved the requirement of these proteins for Syncytin-1 regulation. Thirty primary abnormal placentae from PE, HELLP and IUGR patients compared to 10 controls showed significant deregulation of leptin RNA and protein, p38α, phospho-p38α, PPARγ, ABCG2, INSL4 and Syncytin-1. Our study characterized PPARγ/RXRα signaling in human CT and cell fusions identifying Syncytin-1 as a new target gene. Based on these results, a disturbed PPARγ/RXRα pathway could contribute to pathological human pregnancies.

Ghrelin suppresses nocturnal secretion of luteinizing hormone (LH) and thyroid stimulating hormone (TSH) in patients with major depression.

Major depression is associated with various endocrine disturbances. Apart from the well-known hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis, also the function of the hypothalamic-pituitary-gonadal (HPG) axis and of the hypothalamic-pituitary-thyroid (HPT) axis may be altered compared to healthy subjects. The orexigenic hormone ghrelin is involved in mood regulation and may have antidepressant effects. In addition, it has been shown to suppress secretion of luteinizing hormone (LH) and thyroid stimulating hormone (TSH) in healthy subjects. Aim of this study was therefore to test the effect of ghrelin on the activity of the HPG and HPT axis in patients with major depression. Therefore, secretion profiles of LH and TSH were determined in 14 unmedicated patients with major depression (7 women) twice, receiving 50 µg ghrelin or placebo at 2200, 2300, 0000, and 0100 h. LH secretion after ghrelin injection as assessed by the AUC (4.05 ± 1.18 mlIU min/ml) was significantly (P = 0.049) lower than after placebo injection (4.75 ± 1.33 mlIU min/ml) during the predefined intervention period (2220-0200 h). In addition, LH pulses occurred significantly (P = 0.045) less frequently after ghrelin injection (3.2 ± 1.4) than after placebo injection (3.9 ± 1.7). Mean TSH plasma levels were significantly lower at 0240 h and from 0320 until 0420 h after ghrelin injection than after placebo injection. In conclusion, ghrelin suppressed nocturnal secretion of LH and TSH in patients with major depression. However, these effects were weaker than previously shown in healthy subjects.

Ghrelin suppresses secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in women.

CONTEXT: Ghrelin has been shown to suppress secretion of LH and, less regularly, of FSH in male and female animals and human males. However, no such evidence exists for human females. OBJECTIVE: The aim was to study the effect of ghrelin on secretion of LH and FSH in women. DESIGN/PARTICIPANTS/INTERVENTION: Nocturnal (2000-0700 h) secretion profiles of LH and FSH were determined in six healthy women (age, 25.5±2.9 yr) twice, receiving 50 µg ghrelin or placebo at 2200, 2300, 2400, and 0100 h in this single-blind, randomized, crossover study. RESULTS: LH secretion after ghrelin injection as assessed by the area under the curve (4.01±1.37 mIU/min·ml) was significantly (P=0.031) lower than after placebo injection (5.46±1.33 mIU/min·ml). Also, FSH secretion after ghrelin injection (5.54±0.64 mIU/min·ml) was significantly (P=0.038) lower than after placebo injection (5.87±0.56 mIU/min·ml). LH pulses occurred significantly (P=0.007) less frequently after ghrelin injection (2.3±0.5) than after placebo injection (3.8±0.9). Accordingly, the interval between first and second LH pulse after treatment was significantly (P=0.002) longer after ghrelin injection (300±86 min) than after placebo injection (187±60 min). One of the six women exhibited clear FSH pulses, which overall paralleled LH pulses; two FSH and LH pulses occurred after ghrelin injection, but three occurred after placebo in this woman. CONCLUSIONS: This is the first report that ghrelin suppresses the secretion of LH and FSH in women. These findings resemble those in male and female animals and in men.

Effects of ghrelin on psychopathology, sleep and secretion of cortisol and growth hormone in patients with major depression.

Ghrelin showed antidepressant-like effects in mice. Furthermore, ghrelin influences sleep and the activity of hypothalamic-pituitary-adrenal (HPA) and somatotropic axis in healthy humans as indicated by increased cortisol and growth hormone (GH) plasma levels. Both sleep and the activity of these endocrine axes are disturbed in depression. We therefore studied the impact of ghrelin on psychopathology, sleep and secretion of cortisol and GH in patients with major depression. Depressive symptoms as assessed by a validated self rating scale ('Befindlichkeits-Skala', [mental state scale]), secretion profiles of cortisol and GH and sleep-EEGs were determined in 14 unmedicated patients with major depression (7 women) twice, receiving 50 µg ghrelin or placebo at 22:00, 23:00, 00:00, and 01:00 hours. Overall, depressive symptoms did not change significantly after ghrelin administration (placebo: 37 ± 8; ghrelin: 33 ± 10, p = 0.178). However, there was an improvement at trend level in men (placebo: 36 ± 9 to ghrelin: 30 ± 9, p = 0.093) but not in women. In men, ghrelin was associated with less time awake (placebo: 149.0 ± 11.1; ghrelin: 88.0 ± 12.2 min, p = 0.029) and more non-REM sleep (placebo: 263.2 ± 24.1; ghrelin: 304.9 ± 14.1 min, p = 0.027), in women with less REM sleep (placebo: 108.6 ± 15.7; ghrelin: 74.1 ± 13.8 min, p = 0.031) and longer REM latency (placebo: 49.9 ± 6.5; ghrelin: 85.6 ± 14.1 min, p = 0.019). In both sexes, ghrelin caused strong transient increases of GH and cortisol. In conclusion, our study may provide some initial indication that ghrelin can exert antidepressant effects in patients with major depression. Ghrelin strongly affected sleep and secretion of GH and cortisol in a partly different way as previously reported in healthy subjects.

Ghrelin affects the hypothalamus-pituitary-thyroid axis in humans by increasing free thyroxine and decreasing TSH in plasma.

OBJECTIVE: Ghrelin promotes a positive energy balance, e.g. by increasing food intake. Stimulation of the activity of the hypothalamus-pituitary-thyroid (HPT) axis promotes a negative energy balance, e.g. by increasing energy expenditure. We therefore hypothesized that ghrelin suppresses the HPT axis in humans, counteracting its energy-saving effect. DESIGN AND METHODS: In this single-blind, randomized, cross-over study, we determined secretion patterns of free triiodothyronine (fT(3)), free thyroxine (fT(4)), TSH, and thyroid-binding globulin (TBG) between 2000 and 0700 h in 20 healthy adults (10 males and 10 females, 25.3+/-2.7 years) receiving 50 microg ghrelin or placebo at 2200, 2300, 0000, and 0100 h. RESULTS: FT(4) plasma levels were significantly higher after ghrelin administration than after placebo administration from 0000 h until 0620 h except for the time points at 0100, 0520, and 0600 h. TSH plasma levels were significantly lower from 0200 until the end of the study at 0700 h except for the time points at 0540, 0600, and 0620 h. The relative increase of fT(4) (area under the curve (AUC) 0130-0700 h (ng/dl x min): placebo: 1.31+/-0.03; ghrelin: 1.39+/-0.03; P=0.001) was much weaker than the relative decrease of TSH (AUC 0130-0700 h (mIU/ml x min): placebo: 1.74+/-0.12; ghrelin: 1.32+/-0.12; P=0.007). FT(3) and TBG were not affected. CONCLUSIONS: This is the first study to report that ghrelin affects the HPT axis in humans. The early fT(4) increase was possibly induced by direct ghrelin action on the thyroid where ghrelin receptors have been identified. The TSH decrease might have been caused by ghrelin-mediated inhibition at hypothalamic level by feedback inhibition through fT(4), or both.

Contribution of structural peculiarities of onconase to its high stability and folding kinetics.

Onconase (ONC) from Rana pipiens is the smallest member of the ribonuclease A (RNase A) superfamily. Despite a tertiary structure similar to RNase A, ONC is distinguished by an extremely high thermodynamic stability. In the present paper we have probed the significance of three structural regions, which exhibit structural peculiarities in comparison to RNase A, for the stability of ONC to temperature and guanidine hydrochloride induced denaturation: (i) the N-terminal pyroglutamate residue, (ii) the hydrophobic cluster between helix I and the first beta-sheet, and (iii) the C-terminal disulfide bond. For this purpose, the enzyme variants