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F Zappa

Publications and source records attributed to F Zappa.

7 recordsLinked to original sources
PubMed2006

High resolution dissociative electron attachment to gas phase adenine.

The dissociative electron attachment to the gas phase nucleobase adenine is studied using two different experiments. A double focusing sector field mass spectrometer is utilized for measurements requiring high mass resolution, high sensitivity, and relative ion yields for all the fragment anions and a hemispherical electron monochromator instrument for high electron energy resolution. The negative ion mass spectra are discussed at two different electron energies of 2 and 6 eV. In contrast to previous gas phase studies a number of new negative ions are discovered in the mass spectra. The ion efficiency curves for the negative ions of adenine are measured for the electron energy range from about 0 to 15 eV with an electron energy resolution of about 100 meV. The total anion yield derived via the summation of all measured fragment anions is compared with the total cross section for negative ion formation measured recently without mass spectrometry. For adenine the shape of the two cross section curves agrees well, taking into account the different electron energy resolutions; however, for thymine some peculiar differences are observed.

Adenine↗
PubMed2005

Single-photon imaging at 20,000 frames/s.

A complete two-dimensional imaging system based on a silicon monolithic array of 60 single-photon counters is presented. The fabricated solid-state array is rugged and operates at low voltages. Detection efficiency is higher than 40% in the visible range, and cross talk among 50 microm pixels is lower than 10(-4). The complete system provides a maximum throughput of 20 kframes/s with truly parallel readout and nanosecond gating, thanks to the use of an integrated active quenching circuit for each pixel of the array. We report optical and electrical characterizations of the whole imaging system.

Algorithms↗
PubMed2001

Overexpression of NAD(P)H:quinone oxidoreductase 1 in human reproductive system.

NAD(P)H:quinone oxidoreductase 1 (NQO1; DT-diaphorase; DTD) is a two-electron reductase that efficiently bioactivates compounds of the quinone family, such as mitomycin C. The observation that DTD is overexpressed in many cancerous tissues compared to normal tissues has provided us with a potentially selective target that can be exploited in the design of novel anticancer agents. Because of the relative lack of information on the cell-specific expression of DTD, the purpose of this study was to perform a body mapping of its normal distribution. Tissue samples from various components of the human reproductive system were analyzed by immunohistochemistry. We found strong expression of this enzyme in testicular stromal cells (Leydig cells) and in the epithelium of epididymis, ductuli efferentes, and Fallopian tube. These results suggest that DTD-bioactivated quinones could be responsible for a selective toxicity on these components of the reproductive system and cause clinical problems due to testosterone deficiency and infertility. This observation needs to be investigated in preclinical evaluation of new anticancer quinones and in patients treated with these compounds. (J Histochem Cytochem 49:1187-1188, 2001)

Epididymis↗
PubMed1999

The high-dose sequential (Milan) chemotherapy/PBSC transplantation regimen for patients with lymphoma is not cardiotoxic.

BACKGROUND: The high-dose sequential (HDS) regimen developed in Milan for high-grade lymphomas is very active, but its toxicities are still partly unknown. We evaluated prospectively by doppler-echocardiography the cardiotoxicity of this treatment. PATIENTS AND METHODS: Over seven weeks, 20 patients received a sequence of cyclophosphamide, methotrexate, etoposide, mitoxantrone and melphalan, each at its maximum tolerable dose, and the latter in conjunction with autologous peripheral stem-cell transplantation. Echocardiography was performed at baseline, before administration of mitoxantrone and 2, 6 and 12 months after transplantation. The following parameters of the left ventricular systolic and diastolic functions were determined: end diastolic (LVD) and end systolic (LVS) dimensions, the ejection fraction (EF), and the Doppler derived diastolic parameters: peak velocity of the early (E) and late (A) transmitral flow, the E:A ratio, deceleration time of the E wave (DT) and isovolumetric relaxation time (IVRT). A group of 20 normal volunteers served as control. RESULTS: At baseline, in comparison to controls, the patients had altered diastolic function (diminished E:A ratio) and, although still within the normal range, a slightly reduced systolic function (EF). During treatment or in the course of follow-up none of the patients showed clinical signs or symptoms of cardiac failure, nor significant changes of systolic or diastolic parameters, apart from a transient increase in the E:A ratio after the first three chemotherapy cycles (from 1.14 to 1.37, P < 0.05). The EF remained constant during, and up to six months after, transplantation, decreasing only slightly after one year (from 62% to 59%, P < 0.05). Using analysis of covariance we showed that the major determinants of baseline cardiac function and of its evolution over time were patient age and gender, with previous treatment with anthracyclines having a minor role. CONCLUSIONS: The HDS chemotherapy regimen produced no significant sign of cardiotoxicity up to one year after transplantation in patients with normal baseline cardiac function and no history of cardiac disease, pretreated with up to 550 mg/m2 of doxorubicin.

Adult↗
PubMed1993

[The use of a total parenteral nutrition solution in major gastrointestinal surgery].

This study evaluates the efficacy and tolerance of a complete preparation for TPN, "Trive 1000" consisting of an emulsion of lipids, amino acids and sorbitol, balanced in the substratum with a caloric water ratio of 1 cal/1 ml. The preparation offers sterility and simplicities of use guarantee. 20 patients, subjected to major digestive surgery, were treated. The valuation of the product has been effected through nourishing index of common use and by checking of side effects. The results confirm the handling and the tolerance of "Trive 1000" although in hepatic and nephropathic patients the solution must be used with caution.

Aged↗