The Density of Coronal Plasma in Active Stellar Coronae

We have analyzed high-resolution X-ray spectra of a sample of 22 active stars observed with the High Energy Transmission Grating Spectrometer on {\em Chandra} in order to investigate their coronal plasma density. Densities where investigated using the lines of the He-like ions O VII, Mg XI, and Si XIII. While Si XIII lines in all stars of the sample are compatible with the low-density limit, Mg XI lines betray the presence of high plasma densities ($> 10^{12}$ cm$^{-3}$) for most of the sources with higher X-ray luminosity ($> 10^{30}$ erg/s); stars with higher $L_X$ and $L_X/L_{bol}$ tend to have higher densities at high temperatures. Ratios of O VII lines yield much lower densities of a few $10^{10}$ cm$^{-3}$, indicating that the ``hot'' and ``cool'' plasma resides in physically different structures. Our findings imply remarkably compact coronal structures, especially for the hotter plasma emitting the Mg XI lines characterized by coronal surface filling factor, $f_{MgXI}$, ranging from $10^{-4}$ to $10^{-1}$, while we find $f_{OVII}$ values from a few $10^{-3}$ up to $\sim 1$ for the cooler plasma emitting the O VII lines. We find that $f_{OVII}$ approaches unity at the same stellar surface X-ray flux level as solar active regions, suggesting that these stars become completely covered by active regions. At the same surface flux level, $f_{MgXI}$ is seen to increase more sharply with increasing surface flux. These results appear to support earlier suggestions that hot $10^7$ K plasma in active coronae arises from flaring activity, and that this flaring activity increases markedly once the stellar surface becomes covered with active regions.Comment: 53 pages, 19 figures, accepted for publication in Astrophysical Journal. A version of the paper with higher quality figures is available from http://www.astropa.unipa.it/Library/preprint.htm

Application of an Equilibrium Vaporization Model to the Ablation of Chondritic and Achondritic Meteoroids

We modeled equilibrium vaporization of chondritic and achondritic materials using the MAGMA code. We calculated both instantaneous and integrated element abundances of Na, Mg, Ca, Al, Fe, Si, Ti, and K in chondritic and achondritic meteors. Our results are qualitatively consistent with observations of meteor spectra.Comment: 8 pages, 4 figures; in press, Earth, Moon, and Planets, Meteoroids 2004 conference proceeding

Infusional 5-fluorouracil, cisplatin and mitomycin C in advanced gastric cancer : A low cost effective regimen

Recently, we reported a highly active regimen in advanced gastric cancer including a weekly administration of cisplatin, epidoxorubicin, leucovorin, 5-fluorouracil with the support of filgrastim. In order to simplify the administration and to decrease the toxicity of these drugs, mainly epidoxorubicin-induced alopecia, we designed a regimen including an infusional 5-fluorouracil schedule according to the de Gramont regimen, cisplatin and mitomycin C replacing epidoxorubicin. Forty-five patients with advanced or metastatic gastric cancer were treated with cisplatin 50 mg m−2 i.v. on day 1, every 2 weeks, 6S-stereoisomer-leucovorin 100 mg m−2 i.v. followed by 5-fluorouracil 400 mg m−2 i.v. bolus and 600 mg m−2 i.v. in a 22-h infusion, on days 1 and 2, every 2 weeks, and mitomycin C 7 mg m−2 i.v. bolus on day 2, every 6 weeks. Grades 3–4 toxicities (National Cancer Institute-Common Toxicity Criteria) consisted mainly of neutropenia and thrombocytopenia. Five patients had a complete response and 16 had a partial response for an overall response rate of 46.7% (95% confidence interval, 32.1–61.2%). The median survival was 11 months. The combination of cisplatin, 5-fluorouracil and leucovorin according to de Gramont, and mitomycin C seems to be an active and safe regimen in the treatment of advanced gastric cancer. Because of its low cost it may be suggested for patients not enrolled into clinical trials

Multicenter phase II study of docetaxel plus oxaliplatin combination chemotherapy in patients with advanced gastric cancer: Daegu Gyeongbuk Oncology Group

The present study was conducted to evaluate the efficacy and safety of a combination regimen of docetaxel plus oxaliplatin in patients with advanced gastric cancer. Patients with previously untreated metastatic or recurrent, measurable gastric cancer received intravenous docetaxel 65 mg m−2 plus oxaliplatin 120 mg m−2 on day 1 based on a 3-week cycle. Forty-two patients were enrolled in the current study, among whom 39 were assessable for efficacy and all assessable for toxicity. One complete response and 18 partial responses were confirmed, giving an overall response rate of 45.2% (95% confidence interval (CI); 31.7–59.7%). At a median follow-up of 7.7 months, the median time to progression and median overall survival was 5.7 (95% CI; 4.3–7.2) months and 9.9 (95% CI; 7.8–12.0) months, respectively. Grade 3/4 neutropenia occurred in 11 patients (26.1%) and febrile neutropenia was observed in four patients (9.5%). The common non-haematologic toxicity was fatigue (grade 1/2, 61.9%) and nausea (grade 1/2, 47.7%). The combination of docetaxel and oxaliplatin was found to be well tolerated and effective in patients with advanced gastric cancer

Small but crucial : the novel small heat shock protein Hsp21 mediates stress adaptation and virulence in Candida albicans

Peer reviewedPublisher PD

Vascular Endothelial Growth Factor Receptor-2 Couples Cyclo-Oxygenase-2 with Pro-Angiogenic Actions of Leptin on Human Endothelial Cells

The adipocyte-derived hormone leptin influences the behaviour of a wide range of cell types and is now recognised as a pro-angiogenic and pro-inflammatory factor. In the vasculature, these effects are mediated in part through its direct leptin receptor (ObRb)-driven actions on endothelial cells (ECs) but the mechanisms responsible for these activities have not been established. In this study we sought to more fully define the molecular links between inflammatory and angiogenic responses of leptin-stimulated human ECs../Akt/COX-2 signalling axis is required for leptin's pro-angiogenic actions and that this is regulated upstream by ObRb-dependent activation of VEGFR2. These studies identify a new function for VEGFR2 as a mediator of leptin-stimulated COX-2 expression and angiogenesis and have implications for understanding leptin's regulation of the vasculature in both non-obese and obese individuals