Structure and function of negative feedback loops at the interface of genetic and metabolic networks

The molecular network in an organism consists of transcription/translation regulation, protein-protein interactions/modifications and a metabolic network, together forming a system that allows the cell to respond sensibly to the multiple signal molecules that exist in its environment. A key part of this overall system of molecular regulation is therefore the interface between the genetic and the metabolic network. A motif that occurs very often at this interface is a negative feedback loop used to regulate the level of the signal molecules. In this work we use mathematical models to investigate the steady state and dynamical behaviour of different negative feedback loops. We show, in particular, that feedback loops where the signal molecule does not cause the dissociation of the transcription factor from the DNA respond faster than loops where the molecule acts by sequestering transcription factors off the DNA. We use three examples, the bet, mer and lac systems in E. coli, to illustrate the behaviour of such feedback loops.Comment: 8 pages, 4 figure

Forecasting Hungarian Export Volume

The paper summarizes the research on forecasting the Hungarian export volume. We elaborated a two-step procedure. In the first step we forecasted foreign demand, then in the second step we forecasted Hungarian export using the best outcome of the first step together with real exchange rate and import series. We used several econometric techniques and tested our results statistically by two criteria. We compared the precision and stability of the different forecasts. The ARIMA forecasts were employed as a benchmark. We found that in terms of both criteria foreign demand forecasts were significantly better than those obtained with ARIMA. However, in the case of the Hungarian export volume our results were only better in terms of the stability properties. Therefore the choice between the different forecasting methods was not obvious, so a ’Consensus’ index was also computed as a weighted average of different forecasts, where the weights were negative functions of imprecision and instability.

Recovering a spinning inspiralling compact binary waveform immersed in LIGO-like noise with spinning templates

We investigate the recovery chances of highly spinning waveforms immersed in LIGO S5-like noise by performing a matched filtering with 10^6 randomly chosen spinning waveforms generated with the LAL package. While the masses of the compact binary are reasonably well recovered (slightly overestimated), the same does not hold true for the spins. We show the best fit matches both in the time-domain and the frequency-domain. These encompass some of the spinning characteristics of the signal, but far less than what would be required to identify the astrophysical parameters of the system. An improvement of the matching method is necessary, though may be difficult due to the noisy signal.Comment: 5 pages, 1 figure + 4 figure panels; Proceedings of the Eight Edoardo Amaldi Conference on Gravitational Waves (Amaldi8), New York, 2009; to be published in J. Phys.: Conf. Series (JPCS

Seasonal changes in brain serotonin transporter binding in short 5-HTTLPR-allele carriers but not in long-allele homozygotes

Several findings suggest seasonal variations in the serotonin (5-HT) system. We sought evidence for seasonal variation in the serotonin transporter (5-HTT). We found that length of daylight time in minutes correlates negatively with 5-HTT binding in the putamen and the caudate, with a similar tendency in the thalamus, but no such association in the midbrain. In the putamen, an anatomical region with a dense serotonin innervation that is implicated in processing of aversive stimuli, we found a significant gene*daylight effect with a negative correlation between the 5-HTT binding and daylight time in carriers of the short 5-HTTLPR allele, but not in carriers of the long allele. The neurobiological endophenotype identified here directly links activation studies, showing responses on the neural circuit level, with dynamic changes in transporter expression measured in vivo

Separation and identification of antibacterial chamomile components using OPLC, bioautography and GC-MS

Components of 50% ethanolic chamomile (Matricaria recutica L.) flower extract, previously found antibacterial in a TLC-bioautographic study, were separated and isolated by the use of on-line OPLC, which consisted of an OPLC 50 BS system, an on-line coupled flow-through UV detector, and a manual fraction collector. The collected peaks were investigated by GC-MS analysis and by TLC re-chromatography with subsequent visualization, performed after use of the vanillin-sulphuric acid reagent, or under UV illumination, or applying bioautographic detection. The main compounds of the collected 11 fractions were identified by GC-MS. The results showed that the antibacterial effect of 50% ethanolic extract of chamomile is ascribable to cis-, trans-spiroethers, and the coumarins like herniarin and umbelliferone

The finite representation property for composition, intersection, domain and range

We prove that the nite representation property holds for rep- resentation by partial functions for the signature consisting of composition, intersection, domain and range and for any expansion of this signature by the antidomain, xset, preferential union, maximum iterate and opposite opera- tions. The proof shows that, for all these signatures, the size of base required is bounded by a double-exponential function of the size of the algebra. This establishes that representability of nite algebras is decidable for all these signatures. We also give an example of a signature for which the nite repre- sentation property fails to hold for representation by partial functions

Percutaneous Ethanol Sclerotherapy of Symptomatic Nodules Is Effective and Safe in Pregnant Women: A Study of 13 Patients with an Average Follow-Up of 6.8 Years

Background. Because of the increased risk of surgery, thyroid nodules causing compression signs and/or hyperthyroidism are concerning during pregnancy. Patients and Methods. Six patients with nontoxic cystic, four with nontoxic solid, and three with overt hyperthyroidism caused by toxic nodules were treated with percutaneous ethanol injection therapy (PEI). An average of 0.68 mL ethanol per 1 mL nodule volume was administered. Mean number of PEI treatments for patients was 2.9. Success was defined as the shrinkage of the nodule by more than 50% of the pretreatment volume (V0) and the normalization of TSH and FT4 levels. The average V0 was 15.3 mL. Short-term success was measured prior to labor, whereas long-term success was determined during the final follow-up (an average of 6.8 years). Results. The pressure symptoms decreased in all but one patient after PEI and did not worsen until delivery. The PEI was successful in 11 (85%) and 7 (54%) patients at short-term and long-term follow-up, respectively. Three patients underwent repeat PEI which was successful in 2 patients. Conclusions. PEI is a safe tool and seems to have good short-term results in treating selected symptomatic pregnant patients. Long-term success may require repeat PEI

A New Stellar Atmosphere Grid and Comparisons with HST/STIS Calspec Flux Distributions

The Space Telescope Imaging Spectrograph (STIS) has measured the spectral energy distributions (SEDs) for several stars of types O, B, A, F, and G. These absolute fluxes from the CALSPEC database are fit with a new spectral grid computed from the ATLAS-APOGEE ATLAS9 model atmosphere database using a chi-square minimization technique in four parameters. The quality of the fits are compared for complete LTE grids by Castelli & Kurucz (CK04) and our new comprehensive LTE grid (BOSZ). For the cooler stars, the fits with the MARCS LTE grid are also evaluated, while the hottest stars are also fit with the NLTE Lanz & Hubeny OB star grids. Unfortunately, these NLTE models do not transition smoothly in the infrared to agree with our new BOSZ LTE grid at the NLTE lower limit of Teff =15,000K. The new BOSZ grid is available via the Space Telescope Institute MAST archive and has a much finer sampled IR wavelength scale than CK04, which will facilitate the modeling of stars observed by the James Webb Space Telescope (JWST). Our result for the angular diameter of Sirius agrees with the ground- based interferometric value.Comment: 11 figure

Tumorgenezis és a szomatosztatin hatásmechanizmusának vizsgálata humán hipofízis adenomákban = Tumorigenesis and the effects of somatostatin in human pituitary adenomas

Protein western array módszerrel vizsgáltuk ép és tumoros hypophysis mintákból a fehérjeexpressziót. Humán hypophysis szövetben korábban nem ismert 116 fehérjét detektáltunk, továbbá a hypophysis tumogenezisében feltételezhetően szerepet játszó fehérjéket. A Raf/MEK/ERK és a P13K/Akt/mTOR kaszkádok kulcsfontosságú jelátviteli utak -egymással interakcióban- a sejtnövekedés és tumorgenezis szabályozásában. Hypophysis adenomák vizsgálata során mindkét útvonal kezdeti kaszkádjának felülregulációjára következtethettünk. Az IGF II mRNA binding protein 3 (IMP3) expressziója általában korrelál különböző tumorok agresszivitásával. Vizsgálatunk alapján az IMP 3 mind normális, mind neoplasiás (adenoma, carcinoma) hypophysisben hasonló mértékben expresszálódik. A familiáris izololált hypophysisadenoma (FIPA) autoszomális dominánsan öröklődő megbetegedés. A családok 25%-ában mutatható ki a tumor szuppresszor AIP gén mutációja, amely eltérő fenotípussal jár. A hazánkban eddig identifikált FIPA családok részletes klinikai, genetikai vizsgálatait végeztük el. Nem tisztázott, hogy a hypophysis carcinomák de novo képződnek vagy adenomából alakulnak ki. Egy fiatal hypophysis daganatos nőbeteg 14 éves kórtörténete, a daganat (végül ACTH termelő hypophysis carcinoma) radiológiai, műtéti, morfológiai, hisztokémiai leletei alapján megállapítottuk, hogy a tumor kezdettől fogva agresszív volt, azonban de novo carcinoma jelenléte nem volt igazolható. | Using protein western array to analyse the protein expression of normal and adenomatous pituitary samples disclosed both novel proteins (116) and putative protein candidates for pituitary tumorigenesis. Raf/MEK/ERK and P13K/Akt/mTOR cascades are key signalling pathways interacting with each other to regulate cell growth and tumorigenesis. Our results indicate that in pituitary adenomas both pathways are up-regulated in the initial cascade of the pathways. The IGF II mRNA binding protein 3 (IMP3) is correlated with increased tumor agressiveness. Our results indicate that IMP3 is expressed both in normal and in nepolastic (adenoma, carcinoma) pituitary gland tissues without significant differences in expression levels. Familial isolated pituitary adenoma (FIPA) syndrome is an autosomal dominant disease. In 25% of families with this syndrome, the tumor suppressor AIP gene mutation was identified, these families have distinct phenotype. The FIPA families, identified so far in Hungary, were analysed in detail. It is unclear whether pituitary carcinomas arise de novo or evolve from adenomas. Studying the 14y clinical course, radiographic and operative findings, morphologic/immunohistochemical features of the pituitary tumor (finally an ACTH secreting carcinoma) of a young patient, all suggested that it was an aggressive tumor from the outset, but de novo carcinoma could not be confirme