The synthesis of alumina/silicon carbide composites by self-propagating reactions activated by Teflon is investigated. It is shown that small amounts of this material (i.e. 0.20–0.25 wt.%) guarantee ...the occurrence of self-propagation reactions leading to the formation of a composite. In particular, under argon atmosphere, it consists of well-formed crystals of alumina, fine grained silicon carbide and whiskers-shaped crystallites of SiC. On the other hand, aluminium nitride, silicon carbonitride/silicon cyanide, aluminum oxynitrisilicides and mullite are also found under nitrogen atmosphere. The content of SiC whiskers in the final product increases when powdered polymers (polystyrene, polyethylene, polypropylene) are added to the initial mixture together with Teflon.
Sequenza parziale del gene della Stearoyl-CoA desaturasi nel bufalo. Il gene che codifica per la Stearoyl-CoA desaturasi, enzima coinvolto nella biosintesi degli acidi grassi mono-insaturi, è stato ...sequenziato nel bovino, dove risulta composto da 6 esoni, e in cui sono riferiti numerosi SNPs. Nel presente lavoro è stata definita la sequenza, nella specie bufalina, di una porzione del gene, che comprende il quarto esone, e che si differenzia da quella bovina per una delezione di tre nucleotidi e per 4 mutazioni puntiformi. Le sequenze di 127 bufali appartenenti a quattro popolazioni (Italiana, Greca, Egiziana e Turca), analizzate con il sistema DHPLC Transgenomic WAVE®, hanno evidenziato la presenza di quattro SNPs; il sequenziamento diretto ha dimostrato che uno di questi è causativo (Arginina-Lisina). Sono stati inoltre confrontati gli indici genetici per la percentuale di grasso del latte di 27 tori bufalini italiani sottoposti a prova di progenie che presentavano genotipi diversi allo SNP causativo. L'indice dei tori omozigoti per la Lisina è risultato superiore a quello dei tori eterozigoti e omozigoti per l'Arginina. Poiché la frequenza del genotipo Lisina nella popolazione bufalina italiana, selezionata per la produzione di mozzarella, è molto più elevata che nelle altre (P<0,01), che invece sono state selezionate per la produzione di latte, si ipotizza un effetto positivo del genotipo Lisina sul contenuto di grasso del latte.
Protein disulfide isomerase (PDI, EC 5.3.4.1), an enzyme and chaperone, catalyses disulfide bond formation and rearrangements in protein folding. It is also a subunit in two proteins, the enzyme ...collagen prolyl 4‐hydroxylase and the microsomal triglyceride transfer protein. It consists of two catalytically active domains, a and a′, and two inactive ones, b and b′, all four domains having the thioredoxin fold. Domain b′ contains the primary peptide binding site, but a′ is also critical for several of the major PDI functions. Mass spectrometry was used here to follow the folding pathway of bovine pancreatic ribonuclease A (RNase A) in the presence of three PDI mutants, F449R, Δ455–457, and abb′, and the individual domains a and a′. The first two mutants contained alterations in the last α helix of domain a′, while the third lacked the entire domain a′. All mutants produced genuine, correctly folded RNase A, but the appearance rate of 50% of the product, as compared to wild‐type PDI, was reduced 2.5‐fold in the case of PDI Δ455–457, 7.5‐fold to eightfold in the cases of PDI F449R and PDI abb′, and over 15‐fold in the cases of the individual domains a and a′. In addition, PDI F449R and PDI abb′ affected the distribution of folding intermediates. Domains a and a′ catalyzed the early steps in the folding but no disulfide rearrangements, and therefore the rate observed in the presence of these individual domains was similar to that of the spontaneous process.
Diastolic heart failure Corda, M; Orrù, P; Saiu, F ...
Giornale italiano di nefrologia,
2006 Jan-Feb, Letnik:
23 Suppl 34
Journal Article
Recenzirano
Until recently, the development of heart failure was related exclusively to the acute or chronic impairment in systolic function. Currently, the concept of heart failure not sustained primarily by a ...significant reduction in contractility has been clearly defined by several epidemiological and pathophysiological observations. This condition, defined as 'diastolic heart failure' or 'heart failure with preserved systolic function' can be related to different cardiac diseases with a higher prevalence in the elderly. Afterload mismatch situations, such as hypertension or aortic stenosis, as well as hypertrophic cardiomyopathy or pericardial diseases, determine this common clinical syndrome more frequently. Currently, the treatment of diastolic heart failure is still empirical, as there are few and inconclusive data coming from evidence-based medicine.
To investigate whether bone resorption markers change during pregnancy and lactation, and how they are correlated with human placental lactogen (hPL) and PRL.
Young women before pregnancy, during ...pregnancy and during a 12-month post-delivery period (study group; n = 22); and age- and weight-matched normal cycling women (control group; n = 22) for a 20-month-period participated in the study.
In the study group, women both during pregnancy (from the 8th up to the 38th week) and during a 6-month period of lactation, pyridinoline and deoxypyridinoline urinary levels were significantly higher than those of pre-pregnancy and control women. They returned to basal values at the 12th post-delivery month. During pregnancy there were early and late peak increases, at the 8th and 32nd week, respectively. At the 32nd, 34th, 36th and 38th week of pregnancy, pyridinoline and deoxypyridinoline urinary values were significantly correlated with hPL serum levels.
During pregnancy the maternal bone resorption seems to vary critically at early and late stages. A complete reversal of these variations seems to occur after lactation. Further studies could evaluate if changes in placental function are capable of differently interfering with maternal bone resorption.
To investigate whether endogenous dopaminergic activity is impaired in polycystic ovary syndrome (PCOS)-affected women and is normalized by medical ovariectomy.
Women with PCOS untreated (n = 23) and ...treated for 3 months with GnRH analogue (GnRH-a) administration (n = 10) and normal cycling young women (n = 23) as controls.
Acute blockade of dopaminergic receptors by the IV administration of 5mg of the dopaminergic receptor blocking agent sulpiride (sulpiride test) was performed 3 to 7 days after the initiation of spontaneous menses in cycling women or medroxyprogesterone acetate-induced menses in PCOS women. In PCOS women treated with GnRH-a administration (goserelin depot, 3.6mg SC every 28 days), the sulpiride test was repeated 10 to 15 days after the third GnRH-a administration.
Basal PRL levels and PRL increase induced by sulpiride.
Basal PRL levels and the PRL response to sulpiride were increased in women with PCOS. In women with PCOS medical ovariectomy induced by GnRH-a administration reversed to normal both basal and sulpiride-stimulated PRL levels.
In women with PCOS the abnormal regulation of PRL and presumably of hypothalamic neurotransmitters controlling PRL secretion is not a primary alteration but it is likely dependent on abnormal ovarian functionality.
The Low-Frequency Array (LOFAR) Long-Baseline Calibrator Survey (LBCS) was conducted between 2014 and 2019 in order to obtain a set of suitable calibrators for the LOFAR array. In this paper we ...present the complete survey, building on the preliminary analysis published in 2016 which covered approximately half the survey area. The final catalogue consists of 30006 observations of 24713 sources in the northern sky, selected for a combination of high low-frequency radio flux density and flat spectral index using existing surveys (WENSS, NVSS, VLSS, and MSSS). Approximately one calibrator per square degree, suitable for calibration of \(\geq\) 200 km baselines is identified by the detection of compact flux density, for declinations north of 30 degrees and away from the Galactic plane, with a considerably lower density south of this point due to relative difficulty in selecting flat-spectrum candidate sources in this area of the sky. Use of the VLBA calibrator list, together with statistical arguments by comparison with flux densities from lower-resolution catalogues, allow us to establish a rough flux density scale for the LBCS observations, so that LBCS statistics can be used to estimate compact flux densities on scales between 300 mas and 2 arcsec, for sources observed in the survey. The LBCS can be used to assess the structures of point sources in lower-resolution surveys, with significant reductions in the degree of coherence in these sources on scales between 2 arcsec and 300 mas. The LBCS survey sources show a greater incidence of compact flux density in quasars than in radio galaxies, consistent with unified schemes of radio sources. Comparison with samples of sources from interplanetary scintillation (IPS) studies with the Murchison Widefield Array (MWA) shows consistent patterns of detection of compact structure in sources observed both interferometrically with LOFAR and using IPS.
Objectives: The oral combined formulation of levonorgestrel with estradiol valerate (LNG+EV) has demonstrated to be effective on some postmenopausal symptoms. The availability of a transdermal HRT in ...sequential formulation with 17-β-estradiol plus levonorgestrel (TSE2+TSLNG) induced us to do this control-study with the aim to evaluate the efficacy and safety of both oral and transdermal treatments.
Methods: At baseline, the psychological symptoms with the psychometric scale SCL-90, the bone resorption with the measurement of the urinary levels of pyridinoline and dexoxypirydinoline, and the insulin and lipid metabolism were assessed in 30 postmenopausal women (PMW) and in 18 premenopausal women. Then, the PMW women were randomly divided in three groups: group A (
N=10) assumed EV+LNG, group B (
N=10) did not assume any treatment, group C (
N=10) was treated with TSE2+TSLNG. The length of the study was 12 months. The aforementioned assessments were repeated at different time-intervals up to the end of the study.
Results: The total score of SCL-90, the bone resorption, the levels of LDL-cholesterol, total-cholesterol and the parameters of insulin metabolism were higher in PMW than in premenopausal women. During the study, the SCL-90, the bone resorption, total-cholesterol, and LDL-cholesterol levels significantly decreased only in the groups A and C. By contrast, in the group B bone resorption significantly increased at the 12th month. During the treatments, insulin metabolism did not change in the groups A and B. In the group C the secretion of C-peptide and the C-peptide:insulin ratio after OGTT were significantly higher at the 12th month than before treatment. In all groups the endometrium thickness did not change during the study.
Conclusion: A 12-month of either oral or transdermal HRT containing levonorgestrel seems to exert beneficial effects on the main postmenopausal symptoms without negative interferences on the endometrium.
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