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Biomedical subjects

F Fontana

Publications and source records attributed to F Fontana.

At least 19 recordsLinked to original sources
PubMed2006

Comparison between low-level 50 Hz and 900 MHz electromagnetic stimulation on single channel ionic currents and on firing frequency in dorsal root ganglion isolated neurons.

Alteration of membrane surface charges represents one of the most interesting effects of the electromagnetic exposure on biological structures. Some evidence exists in the case of extremely low frequency whereas the same effect in the radiofrequency range has not been detected. Changes in transmembrane voltages are probably responsible for the mobilization of intracellular calcium described in some previous studies but not confirmed in others. These controversial results may be due to the cell type under examination and/or to the permeability properties of the membranes. According to such a hypothesis, calcium oscillations would be a secondary effect due to the induced change in the membrane voltage and thus dependent on the characteristics of ionic channels present in a particular preparation. Calcium increases could suggest more than one mechanism to explain the biological effects of exposure due to the fact that all the cellular pathways using calcium ions as a second messenger could be, in theory, disturbed by the electromagnetic field exposure. In the present work, we investigate the early phase of the signal transmission in the peripheral nervous system. We present evidence that the firing rate of rat sensory neurons can be modified by 50/60 Hz magnetic field but not by low level 900 MHz fields. The action of the 50/60 Hz magnetic field is biphasic. At first, the number of action potentials increases in time. Following this early phase, the firing rate decreases more rapidly than in control conditions. The explanation can be found at the single-channel level. Dynamic action current recordings in dorsal root ganglion neurons acutely exposed to the electromagnetic field show increased functionality of calcium channels. In parallel, a calcium-activated potassium channel is able to increase its mean open time.

Action Potentials↗
PubMed2004

Prevention of MRSA pneumonia by oral vancomycin decontamination: a randomised trial.

This study was undertaken to assess whether oropharyngeal vancomycin may control oropharyngeal carriage and lower airway infection due to methicillin-resistant Staphylococcus aureus (MRSA) acquired in the intensive care unit (ICU). Secondary endpoints were the emergence of vancomycin-resistant enterococci, vancomycin-intermediate S. aureus and vancomycin consumption. A total of 84 patients, admitted to a medical/surgical ICU and mechanically ventilated for >72 h, were randomly assigned to control (n=42) or test (n=42) group. Both groups received the protocol of selective decontamination of the digestive tract, including polymyxin E, tobramycin and amphotericin B. Patients in the test group received 0.5 g of a 4% vancomycin gel at 6-h intervals in the oropharynx. Lower airway infections due to MRSA acquired on the ICU were reduced in the test group, as was oropharyngeal carriage. Neither vancomycin-resistant enterococci nor vancomycin-intermediate S. aureus were isolated from either surveillance or diagnostic samples during the study period. The vancomycin costs were lower in the test group. This study demonstrates that oropharyngeal vancomycin, which controls intensive care unit-acquired lower airway infections and secondary carriage due to methicillin-resistant Staphylococcus aureus, is cost-effective and safe in terms of vancomycin-resistant enterococci and vancomycin-intermediate Staphylococcus aureus.

Administration, Oral↗
PubMed2004

Autogenous and xenogeneic bone grafts for the bone regeneration. A literature review.

The aim of this article is to investigate 2 groups of biomaterials widely used in the surgical procedures for bone regeneration in dentistry: autograft and xenograft bone. An insufficient bone volume is the main condition for the long life stability of osteointegrated implants. Thanks to the numerous surgical procedures and fervent research, the possibility to rebuild the bone is now much more predictable than in the past. This has provided the clinician with more solutions to handle complex situations. In the last decade, the demand for regenerative surgery for functional and aesthetic reasons has increased. The autogenous bone graft is considered the gold standard material for any regeneration procedures, because of its main properties: it is osteogenetic, osteoinductive and osteoconductive. The autogenous bone can be harvested from 2 different sites: the intraoral and the extraoral sites. Intraoral donor site are the symphysis of the mandible, the mandibular ramus and the maxillary tuberosity. Extraoral donor site are the iliac crest, the tibia and the skull. The xenogeneic bone graft is a graft that has been taken from a donor of another species. These natural materials, thanks to their chemical-physical characteristics similar to those of the human bone, show great osteoconductive properties.

Bone Diseases↗
PubMed2004

[Eating behaviour and body image: epidemiological study on 4,243 senior and junior high school's Italian students].

AIM: This preliminary study is focused on the description of some dysfunctional perceptions of the body's image and eating habits in a large sample of Italian adolescents. METHODS: A total of 4,243 secondary school adolescents were examined in the Tuscany and Liguria regions in north-west Italy. The age of the 2,024 male and 2,219 female adolescents ranged from 12 to 18 years. The Pisa Survey for Eating Disorder (PSED), a questionnaire aimed at examining eating behaviour and self perception of the body image, was administered. RESULTS: Answers given to items considered in this preliminary study have highlighted the recurrence of cognitive distortions and an excessively rigid attitude to bodily self perception, not to mention frequent and often daily dysfunctional eating behaviour. Particularly, females show a more severe attitude to their own body, a stronger desire to lose weight and more resolution to follow a diet. It is also true to say that girls present more often than their male peers irregular eating habits and moments of overeating. Also the recourse to self-induced vomiting, or other coercive expedients, appears to be more typical of female behaviour though this practice was widespread throughout the sample. CONCLUSIONS: The PSED questionnaire has proved to be a useful tool in revealing eating habits and self-perception in the examined sample. The results obtained confirm the urgent need for educational and preventive intervention.

Adolescent↗
PubMed2003

Photodegradation of Pyrimethanil induced by iron(III) in aqueous solutions.

In this study an abiotic process was suggested to evaluate the behaviour of Pyrimethanil (antibotrytic fungicide) in real matrices. This process consists of a photodegradation of the fungicide carried out in the presence of iron(III) in three types of buffer; acetate, phosphate and citrate. The experimental results show that the nature of buffered solutions influences both the rate of disappearance of Pyrimethanil and, in the case of citrate, also the kind of by-products formed during the photodegradation process. For each case examined, the breakdown products were identified by using liquid chromatography (LC) or gas chromatography (GC), coupled with mass spectrometry (MS). The degradation pathways of the fungicide were proposed and the relative kinetic constants were evaluated. The abiotic photodegradation process shows the possibility of different pathways for Pyrimethanil degradation in environmental matrices such as the soil, plants and foodstuffs, where iron (free and/or bonded) is a natural component.

Chromatography, Liquid↗
PubMed2003

Nonconcordant evolutionary history of maternal and paternal lineages in Adriatic sturgeon.

Although analyses of intraspecific variability are an important prerequisite for species identification assays, only a few studies have focused on population genetics and historical biogeography of sturgeon species. Here we present the first study on genetic variability of the last remaining Adriatic sturgeon, Acipenser naccarii, derived from mitochondrial and nuclear DNA. Our mitochondrial DNA analyses arranged individuals into three distinguished mitochondrial DNA haplogroups (Po1, Po2 and Buna). Two haplogroups (Po1 and Buna) were correlated to geographical distribution, whereas the third (Po2) was not. It was, however, very closely related to one lineage of its Ponto-Caspian sister species, A. gueldenstaedtii. The distribution of nuclear markers (microsatellites and amplified fragment length polymorphism) was strongly correlated to geographical distribution. An assignment test based on nuclear data placed no specimen of A. naccarii to A. gueldenstaedtii and vice versa. Therefore, the presence of gueldenstaedtii-like haplotypes within the Po population is either the result of a postglacial introgression or an ancestral polymorphism and does not indicate a hybrid population. The most valuable tool for forensic species identification purposes is one diagnostic deletion separating all A. naccarii from A. gueldenstaedtii. As both A. naccarii populations are genetically differentiated, stocking of sturgeon from the Po River in Italy into waters of the Buna River would jeopardize the genetic differences between both populations and should thus be avoided.

Animals↗
PubMed2001

Opioid peptides attenuate blood pressure increase in acute respiratory failure.

Plasma opioid peptides, norepinephrine, atrial natriuretic factor (ANF) and blood pressure (BP) were assessed in 24 chronic obstructive pulmonary disease patients with acute respiratory failure. Hypoxemic-hypercapnic patients had high BP, beta-endorphin, Met-enkephalin and dynorphin B, whereas hypoxemic-normocapnic and hypoxemic-hypocapnic patients showed normal BP, high beta-endorphin, and normal Met-enkephalin and dynorphin B. Norepinephrine and ANF were high in all patients, particularly in hypoxemic-hypercapnic patients. Infusion with the opioid antagonist naloxone hydrochloride significantly increased systolic blood pressure (SBP) in hypoxemic-hypercapnic (182.0 +/- 3.2 versus 205.1 +/- 3.0 mmHg; P < 0.01), hypoxemic-normocapnic (149.3 +/- 1.8 versus 169.1 +/- 2.2 mmHg; P < 0.01) and hypoxemic-hypocapnic (147.3 +/- 1.3 versus 166.8 +/- 2.2 mmHg; P < 0.01) patients, norepinephrine in hypoxemic-hypercapnic patients (3583.2 +/- 371.8 versus 5371.3 +/- 260.0 fmol/ml; P < 0.01), and reduced ANF in hypoxemic-normocapnic (18.3 +/- 0.8 versus 11.9 +/- 1.0 fmol/ml; P < 0.05) and hypoxemic-hypocapnic (18.1 +/- 1.2 versus 12.1 +/- 2.1 fmol/ml; P < 0.05) patients. These results indicate that the endogenous opioid system attenuates SBP responses in acute respiratory failure by affecting norepinephrine or ANF release.

Acute Disease↗
PubMed2001

Sturgeon genetics and cytogenetics: recent advancements and perspectives.

The aim of this review is to introduce current knowledge in the field of sturgeon genetics. The first section deals with sturgeon cytogenetics, reviewing karyotype organization and polyploidization events during evolution of Acipenseriformes. The second section concerns the results of applications of molecular biology to studies of phylogenetic relationships between extant species, intraspecific analysis of wild populations and stocks for conservation purposes, together with characterization of molecular markers for species identification, relevant to forensic and conservation issues.

Animals↗
PubMed2001

Chromosomal location and evolution of a satellite DNA family in seven sturgeon species.

The Hind III satellite DNA family, isolated from the Acipenser naccarii genome, was used as a probe for fluorescent in-situ hybridization (FISH) on the karyotype of seven sturgeon species, six belonging to the genus Acipenser and one to Huso. All species except one (A. sturio) exhibit from 8 to 80 chromosome hybridization signals, mainly localized at the pericentromeric regions. Eight chromosomes with weak hybridization signals are present in H. huso and A. ruthenus, which are characterized by a karyotype with about 120 chromosomes. The species with 240-260 chromosomes, A. transmontanus, A. naccarii, A. gueldenstaedtii, and A. baerii, show from 50 to 80 signals, prevalently localized around centromeres. Moreover, A. transmontanus and A. gueldenstaedtii show from 4 to 8 chromosomes with a double signal. The phylogenetic and evolutionary relationships among sturgeon species are discussed on the basis of number and morphology of signal-bearing chromosomes and on the localization of signals.

Animals↗
PubMed2001

Identification of interspecific hybrids by amplified fragment length polymorphism: the case of sturgeon.

The identification of interspecific hybrids represents an important issue for conservation biology and trade controls. In Italy, the commercial demand for sturgeon is rapidly increasing and interspecific hybrids represent a relevant part of aquacultural production. In this study we tested the suitability of the amplified fragment length polymorphism (AFLP) technique for sturgeon hybrid detection. Multilocus AFLP profiles were analysed by cluster analysis and assignment tests based on observed and simulated samples. Our results show that this approach can easily identify sturgeon hybrids, encouraging its application not only in sturgeon but also in other systematic groups.

Animals↗
PubMed2000

Mechanisms of hypertension in patients with chronic obstructive pulmonary disease and acute respiratory failure.

PURPOSE: To investigate the effects of hypoxemia, hypercapnia, and cardiovascular hormones (norepinephrine, endothelin-1, and atrial natriuretic factor) on blood pressure during acute respiratory failure. PATIENTS AND METHODS: Patients with chronic obstructive pulmonary disease and acute respiratory failure were divided into four groups of 10 patients each: hypoxemia-normocapnia, hypoxemia-hypercapnia, hypoxemia-hypocapnia, and normoxemia-hypercapnia. Plasma norepinephrine levels were determined by high-performance liquid chromatography with electrochemical detection. Plasma endothelin-1 and atrial natriuretic factor levels were radioimmunoassayed after chromatographic preextraction. RESULTS: Systolic blood pressure and cardiovascular hormone levels were greater in patients with hypercapnia (whether or not they also had hypoxemia) than in those with normocapnia and hypoxemia. For example, in patients with hypercapnia and normoxemia, the mean (+/- SD) systolic blood pressure was 183+/-31 mm Hg and the mean norepinephrine level was 494+/-107 pg/mL, as compared with 150+/- 6 mm Hg and 243+/-58 pg/mL in those with normocapnia and hypoxemia (both P<0.05). Similar results were seen for endothelin-1 and atrial natriuretic factor levels, and for the comparisons of hypoxemic patients who were hypercapnic with those who were normocapnic. CONCLUSIONS: These results suggest that blood carbon dioxide levels, rather than oxygen levels, are responsible for hypertension during acute respiratory failure, perhaps as a result of enhanced sympatho-adrenergic activity.

Acute Disease↗
PubMed2000

Opioid peptide modulation of circulatory response to hyperventilation in humans.

After hyperventilation, systolic blood pressure (SBP) significantly decreased in 10 subjects (group 1), did not change in eight (group 2) and increased in 15 (group 3). Diastolic blood pressure and heart rate increased in all groups. The decrease in SBP was associated with a decrease in plasma catecholamines and increase in beta-endorphin, whereas the increase in SBP was accompanied by an increase in catecholamine and Met-enkephalin levels. Naloxone abolished the hyperventilation-induced SBP and catecholamine decrease only in group 1. These findings show an activation of the endogenous opioid system after hyperventilation and the role of beta-endorphin in reducing SBP in response to the test.

Adult↗
PubMed2000

PVP solid dispersions for the controlled release of furosemide from a floating multiple-unit system.

The poor bioavailability of orally dosed furosemide (FUR) is due to the presence of a biological window in the upper gastrointestinal tract. The purpose of the present study was to develop and optimize in vitro a multiple-unit floating system with increased gastric residence time for FUR. The incomplete release of FUR from the units, related to its low water solubility, led to the preparation and evaluation of different FUR samples to be incorporated into the units. The complete dose release over the actual intragastric residence time of the system (about 8 hr) was achieved by loading both the core and the membrane forming the units with a 1:5 FUR/polyvinylpyrrolidone (FUR/PVP) solid dispersion. Physicochemical analyses suggested the predominant role of the amorphous state of FUR in producing enhanced drug solubility and dissolution rate, which led to the desired release profile from the floating units.

Chemistry, Pharmaceutical↗
PubMed2000

Evaluation of the PuriLens contact lens care system: an automatic care system incorporating UV disinfection and hydrodynamic shear cleaning.

PURPOSE: This study evaluates lens care using the PuriLens System, an advanced way to clean and disinfect soft hydrophilic lenses using subsonic agitation and UV radiation, respectively. METHODS: A two-period crossover lens cleaning and safety investigation was conducted using 80 patients. Disinfecting efficacy was tested in accordance with standard FDA protocols. Lens compatibility was studied with Group I and Group IV lenses during the equivalent of a 6-month care regimen by measuring: lens power, base curve, wet diameter, refractive index, clarity, and tint. Safety was evaluated through slit-lamp findings, wearing time, comfort, and visual acuity. RESULTS: The mean wearing time of patients in the study was 13.79 hours. No slit lamp findings greater than grade 2 were noted. Visual acuity was 20/25 or better in 92.5% of examinations. None of the patients lost more than two lines of acuity. Lens surface evaluation showed no deposits (grade 0) to very slight deposits (grade 1) in 94.4% of examinations. Lenses cleaned with the PuriLens System were cleaner by a statistically significant margin (P=0.02) compared to lenses digitally cleaned with a leading multi-purpose solution (ReNu, Bausch & Lomb). Overall, neither the Group I nor Group IV lenses were affected after 180 cleaning cycles. CONCLUSIONS: The PuriLens System provides automatic lens care compliance, superior antimicrobial efficacy, and eliminates the need for daily digital cleaning.

Adolescent↗