PubMed Health⌕ Search

Biomedical subjects

R Marangoni

Publications and source records attributed to R Marangoni.

At least 19 recordsLinked to original sources
PubMed2003

PaTre: a method for paralogy trees construction.

Genomes can be described as a collection of clusters, the gene families, whose members are called paralogs. Paralogs are genes that most probably share duplication history and show a significant similarity in their sequences, even if they perform slightly different biological function. Among the different mechanisms that have led to an increase of the genomic information during biological evolution, gene duplication is probably the most important. To better understand duplication events, the first step is to investigate the history of the gene families in order to detect which duplication events have taken place, and in which relative (partial) order. Here we present a method, called PaTre, that, given a gene family, attempts to construct the paralogy tree of the family. We will work under the hypothesis that every family member derives from a duplication process of another member. By the term paralogy tree, we mean a directed tree in which the root represents the most ancient paralog of the family and each oriented arc (a, b) represents the existence of a duplication event from the template gene a to its copy b. Notice that gene a survives the event and can serve as a template of more than one duplication event; in fact, there can be more than one arc leaving a. PaTre uses new algorithmic techniques motivated by the specific application at hand. The reliability of the inferential process has been tested by means of a simulator that implements different hypotheses on the duplication-with-modification paradigm and on three examples of different biological gene families, belonging either to lower and higher organisms.

Arabidopsis↗
PubMed2000

Covalent Grafting of Ethylene Glycol into the Zn-Al-CO(3) Layered Double Hydroxide.

Zn-Al-CO(3) layered double hydroxide was synthesized at room temperature using a procedure reported elsewhere. After characterization, 0.5 g of the Zn-Al-CO(3) layered compound was reacted under air with 15 cm(3) of ethylene glycol at 80 degrees C for a period of 5 days. After washing with acetone and drying at 50 degrees C, the resulting white powder was characterized by X-ray powder diffraction, thermal analysis (simultaneous TG/DSC), elemental analysis (C, H, N, Al, and Zn content), and FTIR spectroscopy. All of the experimental data were consistent with the bidentade grafting of ethylene glycol into the interlayer surface of the Al-Zn double hydroxide. The stoichiometry obtained [Zn(0.66)Al(0.34)(OCH(2)CH(2)O)](OH)(0.34).0.4H(2)O] showed that all of the surface hydroxide groups were replaced by ethylene glycol through Al-(Zn)-O-C bonds. Carbonate could not be detected by FTIR, proving that OH(-) was probably the actual intercalated counteranion. Copyright 2000 Academic Press.

Journal Article↗
PubMed2000

Phototactic orientation mechanism in the ciliate Fabrea salina, as inferred from numerical simulations.

The marine ciliate Fabrea salina shows a clear positive phototaxis, but the mechanism by which a single cell is able to detect the direction of light and orient its swimming accordingly is still unknown. A simple model of phototaxis is that of a biased random walk, where the bias due to light can affect one or more of the parameters that characterize a random walk, i.e., the mean speed, the frequency distribution of the angles of directional changes and the frequency of directional changes. Since experimental evidence has shown no effect of light on the mean speed of Fabrea salina, we have excluded models depending on this parameter. We have, therefore, investigated the phototactic orientation of Fabrea salina by computer simulation of two simple models, the first where light affects the frequency distribution of the angles of directional changes (model M1) and the second where the light bias modifies the frequency of directional changes (model M2). Simulated M1 cells directly orient their swimming towards the direction of light, regardless of their current swimming orientation; simulated M2 cells, on the contrary, are unable to actively orient their motion, but remain locked along the light direction once they find it by chance. The simulations show that these two orientation models lead to different macroscopic behaviours of the simulated cell populations. By comparing the results of the simulations with the experimental ones, we have found that the phototactic behaviour of real cells is more similar to that of the M2 model.

Animals↗
PubMed2000

Phototaxis in the ciliated protozoan Ophryoglena flava: dose-effect curves and action spectrum determination.

The sensitivity of positive phototactic orientation of cells of the ciliated protozoan Ophryoglena flava has been measured for white light, broad-band blue and red light, and narrow-band monochromatic light, using a laboratory-developed computer aided system. The white-light fluence rate-response curve shows that there is no negative phototaxis in the fluence rate range investigated (0-15 W/m2) and no adaptation phenomena; it is very well fitted by a hyperbolic function; the fluence rate curves under broad band blue and red light (full width at half maximum, FWHM= 100 nm) can be fitted by the same model. The saturation level is, within experimental errors, the same for the three curves, indicating that there are no chromaticity effects and that if there is more than one photoreceptor pigment, they act independently of each other. The fluence rate-response curves determined under narrow band monochromatic light (FWHM = 10 nm) can also be fitted by the same model and show, within experimental errors, the same saturation level. An action spectrum for positive phototaxis at 10-nm intervals has been calculated from fluence rate-response curves: it shows three maxima, at 420, 540 and 590 nm. This action spectrum is significantly different from the ones for photomotile responses in Blepharisma japonicum, Stentor coeruleus and Chlamydodon mnemosyne, whereas it resembles the ones of Paramecium bursaria and Fabrea salina.

Animals↗
PubMed2000

ELDONET--European Light Dosimeter Network. Structure and functions of the ELDONET server.

The European Light Dosimeter Network (ELDONET) project has been designed with the purpose of establishing an efficient system to monitor solar radiation in Europe, in as many as possible locations. This paper describes the structure of the server that collects and processes the data acquired by the different stations belonging to the network, and makes them freely available on the Internet to the scientific community. The server is able to receive data either via FTP from the Internet or via modem and to process them looking for errors or inconsistencies. Moreover, it automatically generates graphs, Web-pages and FTP archives. The server has been active for some years in testing mode and is now fully operative.

Computer Storage Devices↗
PubMed1995

Lactate versus bicarbonate on-line hemofiltration: a comparative study.

In this study, 6 chronic anuric uremic patients underwent lactate hemofiltration (HF) with a substitution fluid, prepared in bags, for 3 months and bicarbonate HF, with continuous on-line preparation of the substitution fluid, for 3 months. We determined Na+, Cl-, K+, total calcium (Ca), ionized calcium (Ca2+), phosphate, intact parathormone (I-PTH), pH, PCO2, PO2, and HCO3- in plasma before, during, and after the treatment, as well as Ca, Ca2+, phosphate, and I-PTH in the ultrafiltrate. Moreover, heart rate (HR) and mean arterial pressure (MAP) were continually recorded during the procedure. Furthermore, the patients underwent echocardiographic study before and after the session. In comparison with lactate, bicarbonate HF caused a significant increase in HCO3- and a decrease in K+ plasma concentrations. This was detectable, with lower significance, even 44 h after the end of the treatment. At the end of the long interdialytic period (68 h after the end of the treatment), no significant difference was detectable. pH and PCO2 showed a significant but transient increase during HF. The other parameters investigated did not differ significantly between the two methods.

Adult↗
PubMed1993

[Evaluation of bronchiectasia with AMBER and high-resolution computerized tomography. Prospective study of a group of 50 patients].

The authors compared the diagnostic value of AMBER and HRCT in the evaluation of bronchiectasis. A series of 50 patients with conventional X-ray findings suggestive of this condition (increased pulmonary markings, loss of pulmonary volume and segmental cysts) were submitted to HRCT. In all the patients with bronchiectasis (25/50), AMBER showed increased pulmonary markings in one or more localizations, while loss of pulmonary volume was observed in 22 cases and segmental cysts in 8. The positive predictive value (PPV) of these findings was 50% for increased markings, 59% for the loss of pulmonary volume, 64% for the association of the former two signs and finally 100% for segmental cysts. The false-positive cases were due to bronchial wall thickening and to areas of peribronchial fibrosis. On the basis of their findings, the authors conclude that, except for the finding of segmental cysts, AMBER does not allow the unquestionable diagnosis of bronchiectasis to be made due to its low PPV (64%) and that further studies with HRCT are therefore required.

Bronchiectasis↗
PubMed1993

Dislipemia in patients undergoing continuous ambulatory peritoneal dialysis: pharmacological therapy (simvastatin) versus hemodialysis.

Peritoneal dialysis can worsen dislipemia, which is frequent in chronically uremic patients. In order to verify the therapeutic possibilities, we retrospectively studied 20 chronically uremic patients who had been previously treated with continuous ambulatory peritoneal dialysis (CAPD) and who had developed an IV-type dislipemia. Twelve have continued CAPD treatment and have been simultaneously treated with simvastatin; 8 have withdrawn from CAPD and have begun HD, without any antidislipemic pharmacological support. The results, after 3, 6, 12, and 18 months of treatment, showed the following: in patients treated with CAPD and simvastatin, highly significant decreases were noted in total cholesterol (T-cho) and triglycerides (TG) (p < 0.001), and highly significant increases were noted in HDL-cholesterol (HDL-cho) (p < 0.005) and apolipoprotein-A1 (Apo-A1) (p < 0.01). In patients treated with HD, only slightly significant decreases were noted in T-cho (p < 0.01) and TG (p < 0.02), a slightly significant increase in Apo-A1 (p < 0.05), and no significant change in HDL-cho. Apolipoprotein-B showed no change in the two groups. Therefore, patients undergoing CAPD, with dislipemia only, can continue the treatment, because simvastatin is capable of correcting dislipemia, while those patients who have displemia as well as other complications strictly due to CAPD must abandon treatment and must be transferred to extracorporeal methods.

Female↗
PubMed1992

Short time treatment with high-efficiency paired filtration dialysis for chronic renal failure.

With the aim of treating with short sessions even chronic uremic patients with cardiovascular instability, we have developed our previous findings about paired filtration dialysis (hemofiltration-hemodialysis in series) by a method we call high-efficiency paired filtration dialysis (HEPFD). We have treated with this method for 6 months 6 chronic anuric uremic patients previously treated for 6 months with hemofiltration (HF) because of their cardiovascular instability. By comparison with HF, HEPFD shows much higher clearances of small molecules with consequent significant decrease of their predialytic values, improvement of Kt/V value, lower beta 2-microglobulin clearance (its predialytic value remains unchanged), and the same tolerability. HEPFD allows short, efficient, and well-tolerated treatments even in patients with cardiovascular instability.

Adult↗
PubMed1992

Plasma lipids and fatty acid levels in chronically uremic patients undergoing blood purification with different methods.

Levels of plasma lipids and the fatty acid composition of major plasma lipid classes have been determined in chronically uremic patients before and after treatments with hemofiltration, high efficiency paired filtration dialysis, or acetate-free biofiltration. The major findings are a decrease of triglycerides and an increase of total free fatty acids (FFAs) at the end of the dialytic session--already reported in the literature--that do not appear to be strictly dependent on heparin administration. The changes in the plasma concentrations of selected saturated and polyunsaturated fatty acids, which may contribute to alteration of functional parameters in the cardiovascular system in dialyzed patients, are different in the various types of techniques.

Adult↗
PubMed1992

[Computerized tomography as a diagnostic complement of standard radiograms in the evaluation of traumatic lesions of the carpal scaphoid. A study of 10 cases].

The authors investigated the value of direct coronal CT as a diagnostic complement to plain radiography in the assessment of post-traumatic scaphoid conditions. The series included 10 patients who were selected either for disagreement of clinical and radiological findings, the latter being negative (3 patients), or for better assessment of radiological findings, which had diagnosed bone lesions, in order to plan treatment (7 cases). CT provided additional information in 5 patients, demonstrating 2 nonunited fractures in the first group and 2 pseudoarthroses with no significant bone deformity and 1 osteonecrosis in the second group. These results, which proved essential to plan the subsequent treatment, show that CT has, at present, in specific cases, a definite role in evaluating post-traumatic scaphoid conditions, and stress the value of direct coronal images, which are both easy to interpret, being equivalent to radiographs in postero-anterior projection, and quick to perform.

Adult↗
PubMed1990

Improvement of continuous arteriovenous hemofiltration (CAVH) and hemofiltration (HF) efficiency by adding hemoperfusion (HP).

Aiming to improve the efficiency of the blood purification convective methods either with spontaneous (CAVH) or with pump-assisted (HF) extracorporeal circulation we inserted after the hemofilter a cartridge containing 70 g of collodion-coated activated charcoal (CAC) microencapsulated, obtaining so hemofiltration and hemoperfusion in series (HF+HP). The obtained results show that in both methods HP addition gives a negligible increase of urea clearance and a practically null increase of phosphate clearance, whereas creatinine and uric acid clearances increase is remarkable especially, in percentage, with low blood flows (CAVH). In the HF+HP system we have also been studying B2-microglobulin (B2-M) clearance aiming at examining the possibility of increasing the removal of substances with higher molecular weight. We have been finding HP addition increases further on B2-M clearance already high in HF. Therefore we think HP addition to convective methods is an interesting step in the attempt to carry out highly efficient blood purification methods.

Creatinine↗
PubMed1989

[Hemofiltration and hemoperfusion performed in series for the purpose of removing beta 2 microglobulin].

With the objective to develop most efficient method for Beta-2-microglobulin elimination, the authors, using extracorporeal circulation placed behind the haemofilter a capsule containing 70 g of collodion coated with activated medicinal charcoal. This combination was used in 3 haemofilters made from different membranes. The results showed polysulphon to be the highest efficiency membrane out of those tested for Beta-2 microglobulin elimination. In combination with haemoperfusion, its efficiency increases significantly. Even if haemoperfusion increases efficiency by considerable percentage, the Beta-2 microglobulin elimination using other types of membranes lasts long and the total clearance remains low.

Adult↗
PubMed1979

[Nicergoline and platelet aggregation. A review of experimental and clinical studies (author's transl)].

10-Methoxy-1,6-dimethyl-ergoline-8 beta-methanol-(5-bromonicotinate) (nicergoline, Sermion), an ergoline derivative in clinical use for syndromes related to cerebral and peripheral vascular insufficiency, displays a platelet antiaggregating effect which may be important for its therapeutic effect. This paper reviews the present experimental and clinical evidence relating to the platelet antiaggregating activity of nicergoline and its mechanisms of action is discussed in detail. Since the platelet antiaggregating effect of nicergoline is mainly related to its alpha-adrenolytic activity, the importance of catecholamines for the behaviour of both human platelets and endothelium as well as their interference with the prostaglandin/prostacycline system is also discussed.

Ergolines↗