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Biomedical subjects

E Longo

Publications and source records attributed to E Longo.

At least 19 recordsLinked to original sources
PubMed2004

Quantitative analysis and classification of AFM images of human hair.

The surface topography of human hair, as defined by the outer layer of cellular sheets, termed cuticles, largely determines the cosmetic properties of the hair. The condition of the cuticles is of great cosmetic importance, but also has the potential to aid diagnosis in the medical and forensic sciences. Atomic force microscopy (AFM) has been demonstrated to offer unique advantages for analysis of the hair surface, mainly due to the high image resolution and the ease of sample preparation. This article presents an algorithm for the automatic analysis of AFM images of human hair. The cuticular structure is characterized using a series of descriptors, such as step height, tilt angle and cuticle density, allowing quantitative analysis and comparison of different images. The usefulness of this approach is demonstrated by a classification study. Thirty-eight AFM images were measured, consisting of hair samples from (a) untreated and bleached hair samples, and (b) the root and distal ends of the hair fibre. The multivariate classification technique partial least squares discriminant analysis is used to test the ability of the algorithm to characterize the images according to the properties of the hair samples. Most of the images (86%) were found to be classified correctly.

Algorithms↗
PubMed2003

Sulfide and sulfoxide oxidations by mono- and diperoxo complexes of molybdenum. A density functional study.

The molecular mechanism for the oxidation of sulfides to sulfoxides and subsequent oxidation to sulfones by diperoxo, MoO(O(2))(2)(OPH(3)) (I), and monoperoxo, MoO(2)(O(2))(OPH(3)) (II), complexes of molybdenum was studied using density functional calculations at the b3lyp level and the transition state theory. Complexes I and II were both found to be active species. Sulfide oxidation by I or II shows similar activation free energy values of 18.5 and 20.9 kcal/mol, respectively, whereas sulfoxides are oxidized by I (deltaG = 20.6 kcal/mol) rather than by II (deltaG = 30.3 kcal/mol). Calculated kinetic and thermodynamic parameters account for the spontaneous overoxidation of sulfides to sulfones as has been experimentally observed. The charge decomposition analysis (CDA) of the calculated transition structures of sulfide and sulfoxide oxidations revealed that I and II are stronger electrophilic oxidants toward sulfides than they are toward sulfoxides.

Journal Article↗
PubMed2003

Synthesis of metal-oxide matrix with embedded nickel nanoparticles by a bottom-up chemical process.

Here we describe a new chemical route for obtaining highly dispersed nanometric Ni particles embedded in different matrices based on Al2O3, MgO, and TiO2 and in the heterogeneous matrices CeO2-doped Al2O3 and MgO-doped Al2O3. The synthesis method is based on a modification of the polymeric precursor method. The Ni nanoparticles (particles in the range of 1-40 nm) were obtained in a single process, without the use of an external reducing agent (hydrogen atmosphere).

Aluminum Oxide↗
PubMed2002

Application of Ni:SiO2 nanocomposite to control the carbon deposition on the carbon dioxide reforming of methane.

Stable Ni nanoparticles embedded in a mesoporous silica material were used as catalysts for the conversion of methane into synthesis gas. This catalyst has the singular properties of controlling the carbon deposition and deactivation of active sites. A comparative study of our nanocomposites with conventional catalysts showed that impregnation material presented a preferential encapsulation and growth of carbon nanotubes on the metal surface. The impregnated catalyst showed a higher tendency for carbon nanotube and whiskers formation.

Carbon↗
PubMed2002

Synthesis of mesoporous silica with embedded nickel nanoparticles for catalyst applications.

Here we describe a new route for the synthesis of nanometric Ni particles embedded in a mesoporous silica material with excellent potential for catalytic applications. Mesoporous silica with a surface area in the range of 202-280 m2/g, with narrow pore size distribution and Ni nanoparticles (particles in the range of 3-41 nm) were obtained in a direct process. A different approach was adopted to process such a nanocomposite. This new approach is based on the formation of a polymer with the silicon oxianion and nickel cation chelated to the macromolecule structure and on the control of the pyrolysis step. The CO/CO2 atmosphere resulting from the pyrolysis of the organic material promotes the reduction of the Ni citrate.

Bicyclic Monoterpenes↗
PubMed2002

Synthesis of SnO2 nanoribbons by a carbothermal reduction process.

This communication describes, for the first time, the growth of SnO2 nanoribbons by a controlled carbothermal reduction process. An analysis of the transmission electron microscopy image revealed that these nanoribbons have a well-defined shape, with a typical width in the range of 70-300 nm. In general, the nanostructured ribbons were more than 100 microns in length. The results reported here support the hypothesis that this ribbon-like nanostructured material grows by a vapor-solid process. This study introduces two hypotheses to explain the SnO2 nanoribbon growth process.

Carbon↗
PubMed2001

Molecular structure of the molybdenum oxo-diperoxo compound MoO(O(2))(2)(OPy)(H(2)O): a computational and X-ray study.

We have carried out a combined experimental and theoretical study of the molecular structure of the MoO(O(2))(2)(OPy)(H(2)O) coordination compound using X-ray crystallography and DFT-B3LYP computational method, respectively. The MoO(O(2))(2)(OPy)(H(2)O) complex crystallizes in the orthorhombic space group Pmna with Z = 4, a = 6.9001(9) A, b = 8.0471(1) A, c = 16.227(2) A, V = 901.0(2) A(3), and the X-ray data analysis yields a bipyramidal-pentagonal coordination polyhedron for the Mo atom. The pyridine N-oxide (OPy) ligand occupies the equatorial position, with the oxygen atom of this ligand being located in the same plane as the four peroxo oxygen atoms. The H(2)O ligand is situated trans to the oxo group, forming intermolecular hydrogen bonds with peroxo groups belonging to two adjacent complexes. In our theoretical approach these intermolecular interactions were taken into account by including two methanol molecules which form hydrogen bonds with the water ligand leading to a good agreement between the calculated and the experimental geometry. Our results suggest that it is necessary to take into account the presence of these interactions in order to reconcile the theoretical results to the experimental data, in particular the distance between Mo and the oxygen of water ligand. These results seem to be a general feature for analogous bis-peroxo complexes that have been reported in the literature.

Journal Article↗
PubMed1999

Gender affects the pattern of neuroendocrine response to head-up tilt.

One of the major concerns in space medicine is post-mission postural hypotension. Since the beginning, most of the studies have been aimed at the identification of mechanical and neuroautonomic mechanisms within the cardiovascular system potentially involved in this phenomenon. Some gender differences in the cardiovascular reactivity to changing posture have been described so far, which still need better clarification. Moreover, the neuroendocrine contribution to postflight readaptation deserves more indepth studies. Sudden passive head-up tilting is considered to be a good simulation method for hemodynamic changes occurring during transition from 0xg to 1xg. The aim of this study was to verify whether cardiovascular or neuroendocrine changes occurring after sudden passive +70 degrees head-up tilt (HUT) became already evident within 10 min and were similar in healthy young-adult men and women.

Adaptation, Physiological↗
PubMed1996

[Immune complex detection in nasal mucosa of patients with chronic and permanent nasal obstruction].

Thirty patients with rhinologic problems and in which the main symptom was "Permanent Nasal Blockade" were studied. We found that they presented a "Permanent and Total Chronic Nasal Blockade"-an entity defined by us as a permanent chronic obstruction of the nasal cavities that would be the clinical and anatomopathologic expression and the immunological terminal phase of "Chronic Rhinitis", leading to Chronic Respiratory Nasal Insufficiency. The main symptoms of these "buccal breathers" were: throat dryness, night snores, nasal resonance of the voice, mechanic and secondary disturbances derived from mouth breathing, such as pharingitis, laryngitis, bronchitis, bronchial asthma and a tendency towards emphysema; dystrophia of the facial bones, disminution of the intellectual capacity, irritability, lack of concentration; disturbances of the circulatory function (alterations of the cardiac rhythm and of the blood pressure). The patients were adolescents and young adults in which allergic and infectious causes dominated the etiology, showed by family allergic and personal atopic antecedents, positive intradermic tests for aeroallergenes and bacteria and corroborated by increase of immunoglobulin E and of blood eosinophiles. The methods of diagnosis used to verify the "Permanent and Total Chronic Nasal Blockade" were: X-rays, lineal tomography; rhinomanometry and rhinofibrolaringoscopy. The anatomopathologic results obtained by nasal biopsy showed a lymphomonocitary infiltrate around arterioles and venules: signs of vasculitis. All this led us to search for immunocomplexes. The presence of positive immunocomplexes surrounding the vessels contributed to a more precise focusing of the physiopathology, diagnosis and treatment of "Permanent and Total Chronic Nasal Blockade".

Adolescent↗
PubMed1993

Genetic evidence of a new flocculation suppressor gene in Saccharomyces cerevisiae.

The flocculation character in strain IM1-8b of Saccharomyces cerevisiae is controlled by a single and dominant gene shown to be allelic to FLO1. Such a gene has been both mitotically and meiotically mapped on the right arm of chromosome I at 4.7 cM from PHO11. The phenotype was suppressed by a single gene of wide distribution among non-flocculent strains (proposed as fsu3) that, however, was unable to suppress other FLO1 genes in other flocculent strains.

Alleles↗
PubMed1993

Chromosomal rearrangements during vegetative growth of a wild strain of Saccharomyces cerevisiae.

Electrophoretic karyotypes of two strains of Saccharomyces cerevisiae, a haploid laboratory strain and a wild strain known to be at least diploid, have been checked during vegetative growth. The karyotype of the haploid strain was very stable; however, the diploid strain underwent frequent modifications. In most cases the number of bands was reduced, but occasionally we observed one band splitting into two. In one case, chromosomal rearrangements took place between differently sized copies of chromosomes I and VI. We concluded that the chromosome length polymorphism observed among wild strains of S. cerevisiae could be explained partly by chromosomal structure reorganization occurring during mitosis.

Chromosomes, Fungal↗
PubMed1992

Characterization of killer-resistant strains of Saccharomyces cerevisiae isolated from spontaneous fermentations.

A study of 26 killer-resistant wine strains of Saccharomyces cerevisiae, isolated during spontaneous fermentations in three vineyards in NW Spain, was carried out employing several methods that included a spheroplast-killing assay and analysis of chromosomal DNA patterns by pulse-field agarose electrophoresis. The results showed that 92% of the strains were derivatives of K2 killer toxin producing wine strains isolated from the same fermentations, and that they could be grouped into four different karyotypes. The remaining strains were killer-resistant at cell-wall level and were not related to the others, as was demonstrated by the absence of L and M ds-RNAs and by their different karyotypes.

DNA, Fungal↗
PubMed1990

Experience and implantation techniques with a new single-pass lead VDD pacing system.

Thirty-six patients were implanted with a single-lead atrial-synchronous ventricular pacing (VDD) system at our center in the first and second phases of a clinical trial between October 1987 and December 1989. The clinical system comprised a pulse generator in conjunction with a pacing lead incorporating two diagonal atrial bipolar (DAB) electrodes designed to lie in the mid-to upper-right atrium and a distal tip electrode for ventricular pacing and sensing. Twenty five of the patients had complete heart block, ten had second-degree block, and one had AV nodal block. A modified Bruce protocol limiting treadmill speed to 1.7 miles per hour was used to establish sinus node competency as evidenced by sustained sinus rate increase in a more-or-less linear fashion. The mean acute P wave amplitude measured at implant was 1.66 mV +/- 1.04 SD; the mean P wave amplitude (minimum and maximum, both sitting and supine) for all patients at all follow-up (N = 420) was 1.54 mV +/- 0.9 SD. The follow-up interval for all patients ranged from a minimum of 13 days and a maximum of 762 days, with a mean of 261 +/- 206 days as of December 1, 1989. Four dislodgments of the ventricular electrode occurred with the more pliable of two passive fixation mechanisms used on the lead; atrial sensing remained intact at all times with both fixation systems. Changes in atrial sensing threshold were quite frequent during the early follow-up visits due to electrode movement in the right atrium; however, adequate ventricular tracking of the atrial rate was achieved in all cases once the threshold values were established initially, even though several patients required atrial sensing of 0.2 mV at some of the follow-up visits. Two patients presented with pacemaker-mediated tachycardia associated with retrograde conduction, which was resolved with reprogramming; they are presently maintaining atrial synchrony in the VDD mode. Successful single-lead VDD pacing with consistent P wave sensing has been achieved with this atrial rate responsive system.

Adult↗
PubMed1990

Osmotic activation of Na(+)-H+ exchange in human endothelial cells.

Regulation of intracellular pH (pHi) via a Na(+)-H+ exchange-dependent mechanism was studied in cultured human umbilical vein endothelial cells (HEC) using the pH-sensitive fluorescent dye 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein, as well as measuring 22Na influx. Basal pHi of HEC incubated in a bicarbonate-free Na+ medium was 6.99 +/- 0.03. In HEC that had been acid-loaded using nigericin or a NH4Cl prepulse, pHi recovery occurred via a Na(+)-dependent mechanism that was inhibited by 5-(N-ethyl-N-isopropyl)amiloride (EIPA). The potency of amiloride derivatives to inhibit 22Na influx was EIPA greater than 5-(N,N-dimethyl)amiloride greater than amiloride [Ki (extracellular Na = 30 mM) = 17 nM, 150 nM, and 8.8 microM, respectively]. EIPA-sensitive 22Na influx in acid-loaded HEC was a saturable function of the external Na+ concentration (0-130 mM), exhibiting an approximate Km and Vmax of 19.70 +/- 0.14 mM and 34.01 +/- 2.2 nmol.10(6) cells-1.min-1, respectively. H+ efflux was also dependent on external Na+ and blocked by EIPA. At resting pHi, HEC Na(+)-H+ exchange was slightly stimulated by increases in medium osmolality. However, when HEC were acid-loaded in the presence of hypertonic (sucrose) medium, Na(+)-H+ exchange activity (22Na influx or pHi recovery) increased markedly. Overall, these data indicate that pHi in cultured HEC can be regulated by a Na(+)-H+ exchanger and that its activity can be markedly influenced by osmolality at acidic pHi.

Amiloride↗
PubMed1990

[Intestinal parasitoses in the Galician population].

To evaluate the relative importance of the different intestinal parasites in Galicia, we report the results of the investigation of 6,554 samples of feces in the Microbiology Service of the Hospital General de Galicia (Santiago) from 1983 to 1987. The results indicate that the yearly frequency of parasitism has been reduced from 27.8% of the investigated samples en 1983 to 12.1% in 1987. The mean value for the study period was 16.8% (15.6% simple parasitism and 1.2% multiple parasitism). There were no differences in incidence depending on sex. The enteric parasites most commonly found were G. lamblia, T. trichiura, A. lumbricoides and E. coli.

Cohort Studies↗
PubMed1989

Curing of the killer character of Saccharomyces cerevisiae with acridine orange.

Acridine orange, an intercalating dye usually employed in the curing of bacterial plasmids, was tested for its ability to cure K1 and K2 killer strains (laboratory and wine strains). The results showed a high curing percentage of the killer character. This was demonstrated by the loss of M1 or M2 dsRNAs (responsible for toxin production and resistance to it) and because the meiotic products exhibited non-Mendelian segregation. The curing percentages varied, depending on the strain but not on the killer type, and showed similar efficiency as compared with other known curing agents.

Acridine Orange↗
PubMed1989

[Yeasts associated with spontaneous fermentation processes in wines from Ribeiro. Analysis of homo/heterothallism and the killer system of S. cerevisiae strains].

A taxonomic analysis has been carried out concerning the different yeast species involved in spontaneous fermentations of Ribeiro wine. The results revealed the presence of 15 species belonging to 7 genera: Saccharomyces, Torulaspora, Dekkera, Saccharomycodes, Debaryomyces, Kloeckera and Candida. Within the genus Candida a high number of species was detected. The 28 isolated strains of S. cerevisiae showed with some exceptions, a remarkable sporulation ability and viability of the meiotic products. All the strains were homothallic. Among all S. cerevisiae strains, 6 exhibited killer K2 activity with higher isolation percentages in intermediate fermentations than in late fermentations.

Fermentation↗