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Biomedical subjects

F Orsini

Publications and source records attributed to F Orsini.

At least 19 recordsLinked to original sources
PubMed2006

Protective effect of rhubarb derivatives on amyloid beta (1-42) peptide-induced apoptosis in IMR-32 cells: a case of nutrigenomic.

Amyloid beta (1-42) peptide is considered responsible for the formation of senile plaques that accumulate in the brains of patients with Alzheimer's disease (AD). In the last years considerable attention has been focused on identifying natural food products, such as phytochemicals that prevent or almost retard the appearance of amyloid beta (1-42)-related neurotoxic effects. In this study, human neuroblastoma cells (IMR-32) was used as system model to evaluate the protective role of rhaponticin (3,3',5-trihydroxy-4'-methoxystilbene 3-O-d-glucoside) a stilbene glucoside extracted from rhubarb roots (Rhei rhizoma) and rhapontigenin, its aglycone metabolite, against amyloid beta (1-42)-dependent toxicity. The obtained results show that rhapontigenin maintains significant cell viability in a dose-dependent manner and it exerts a protective effect on mitochondrial functionality, as evidenced by mitochondrial oxygen consumption experiments. A similar behaviour, but to a lesser extent, has been shown by rhaponticin. The protective mechanism mediated by the two stilbenes could be related to their effect on bcl-2 gene family expression. Bax, a pro-apoptotic gene, resulted down-regulated by the treatment with rhaponticin and rhapontigenin compared with the results obtained in the presence of amyloid beta (1-42) peptide. Conversely, bcl-2, an anti-apoptotic gene, highly down-regulated by amyloid beta (1-42) treatment, resulted expressed in the presence of stilbenes similarly to that shown by control cells. The obtained results support the hypothesis that amyloid beta (1-42)-induced neurotoxicity occurs via bax over-expression, bcl-2 down-regulation, firstly indicating that rhaponticin and its aglycone moiety may alter this cell death pathway. Based on these studies, we suggest that rhaponticin and its main metabolite could be developed as agents for the management of AD.

Alzheimer Disease↗
PubMed2006

Dioxygenation of naphthalene by Pseudomonas fluorescens N3 dioxygenase: optimization of the process parameters.

The bioconversion of naphthalene to the 1,2-dihydro-1,2-dihydroxy derivative was performed in good yield using an Escherichia coli recombinant strain carrying Pseudomonas fluorescens N3 dioxygenase. However, the efficiency of such transformation is affected by many process parameters, and their optimization is essential to the scaling up of the process. The following process parameters were considered for optimization: cell concentration together with the corresponding glucose concentration (DCW/L); pH of medium; temperature; stirring speed; air flow; substrate concentration; Fe(2+) concentration; microelements concentration; reaction volume. We used a two-step multivariate experimental design to select important variables and assign them optimal values. The most significant parameters were selected by adopting a Plackett-Burman design, and were then correlated, using a full factorial design, with the experimental results. The experimental results illustrate that the optimized process of recombinant whole cell biotransformation in two-liquid phase systems enhances the naphthalene dihydrodiol yield threefold. This biotransformation opens the way to future experiments involving different substrates.

Bacterial Proteins↗
PubMed2006

Alzheimer's amyloid beta-peptide (1-42) induces cell death in human neuroblastoma via bax/bcl-2 ratio increase: an intriguing role for methionine 35.

The beta amyloid (Abeta), the major protein component of brain senile plaques in Alzheimer's disease, is known to be directly responsible for the production of free radicals toxic to brain tissue and the redox state of Met-35 residue seems to play a particular and critical role in peptide's neurotoxic actions. In this study, we investigated, in human neuroblastoma cells (IMR-32), the relationship between the oxidative state of methionine, and both neurotoxic and pro-apoptotic actions induced by Abeta-peptide, comparing the effects of native peptide, in which the Met-35 is present in the reduced state, with those of a modified peptide with oxidized Met-35 (Abeta(1-42)(35Met-ox)), as well as an Abeta-derivative with Met-35 substituted with norleucine (Abeta(1-42)(35Nle)). The obtained results show that Abeta induces a time-dependent decrease in cell viability; Abeta(1-42)(35Met-ox) was significantly less potent, though inducing a remarkable decrease in cell viability compared to control. On the contrary, no toxic effects were observed after treatment with Abeta(1-42)(35Nle). Abeta-peptide as well as the amyloid modified peptide with oxidized Met-35 induced the pro-apoptotic gene bax over-expression after 24 h, whereas Abeta(1-42)(35Nle) had no effect. Conversely, bcl-2, an anti-apoptotic gene, became highly down-regulated by Abeta peptide treatment, in contrast to that evidenced by the Abeta(1-42)(35Met-ox) peptide. Finally, Abeta caused an increase in caspase-3 activity to be higher with respect to that shown by Abeta(1-42)(35Met-ox) while Abeta(1-42)(35Nle) had no effect. These results support the hypothesis that Abeta-induced neurotoxicity occurs via bax over-expression, bcl-2 down-regulation, and caspase-3 activation, first indicating that methionine 35 redox state may alter this cell death pathway.

Alzheimer Disease↗
PubMed2006

Atomic force microscopy characterization of Xenopus laevis oocyte plasma membrane.

We used atomic force microscopy (AFM) to characterize the plasma membrane of Xenopus laevis oocytes. The samples were prepared according to novel protocols, which allowed the investigation of the extra- and intracellular sides of the membrane, both of which showed sparsely distributed spherical-like protrusions. Regions with comparably sized and densely packed structures arranged in an orderly manner were visualized and dimensionally characterized. In particular, two different arrangements, hexagonal and square packing, were recognizable in ordered regions. The lateral dimension of structures visualized on the external side had a normal distribution centered on 25.5 +/- 0.3 nm (mean value +/- SE), whereas that on the intracellular side showed a normal distribution centered on 30.2 +/- 0.8 nm. The height of the protrusions was 2-5 nm on the external side and 1-3 nm on the intracellular side. The mean number of structures on the external and intracellular sides of the plasma membrane was about 1000 microm(-2) and 850 microm(-2) respectively. Trypsin treatment greatly decreased the size of the membrane protrusions, thus confirming the proteic nature of the structures. These results show that AFM is a useful tool for structural characterization of proteins in a native eukaryotic membrane.

Animals↗
PubMed2006

Atomic force microscopy imaging of actin cortical cytoskeleton of Xenopus laevis oocyte.

In this study we report an atomic force microscopy (AFM) investigation of the actin cortical cytoskeleton of Xenopus laevis oocytes. Samples consisted of inside-out orientated plasma membrane patches of X. laevis oocytes with overhanging cytoplasmic material. They were spread on a freshly cleaved mica surface, subsequently treated with Triton X-100 detergent and chemically fixed. The presence of actin fibres in oocyte patches was proved by fluorescence microscopy imaging. Contact mode AFM imaging was performed in air in constant force conditions. Reproducible high-resolution AFM images of a filamentous structure were obtained. The filamentous structure was identified as an actin cortical cytoskeleton, investigating its disaggregation induced by cytochalasin D treatment. The thinnest fibres showed a height of 7 nm in accordance with the diameter of a single actin microfilament. The results suggest that AFM imaging can be used for the high-resolution study of the actin cortical cytoskeleton of the X. laevis oocyte and its modifications mediated by the action of drugs and toxins.

Actins↗
PubMed2004

Resveratrol derivatives and their role as potassium channels modulators.

A series of stilbenoid analogues of resveratrol (trans-3,4',5-trihydroxystilbene) with a stilbenic or a bibenzylic skeleton have been prepared by partial synthesis from resveratrol and dihydroresveratrol. The synthesized compounds have been evaluated for their ability to modulate voltage-gated channels.

Animals↗
PubMed2003

Poly(lactide-co-glycolide) microspheres containing bupivacaine: comparison between gamma and beta irradiation effects.

The beta- and gamma-irradiation effects on stability of microspheres made of poly(lactide-co-glycolide) 50:50 copolymer (PLGA) containing bupivacaine (BU) were studied. Microspheres containing 10, 25, and 40% w/w, respectively, of BU were prepared by spray drying and irradiated in air with beta- and gamma-irradiation at a dose of 25 kGy. Morphology (atomic force microscopy, particle-size analysis), physico-chemical characteristics (DSC and FT-IR spectroscopy), drug content and in vitro dissolution profile of microspheres were all determined; the stability of irradiated microspheres was evaluated over a 9-month period. The decrease of BU content in gamma-irradiated microspheres was almost always constant independent of the amount of BU per sample, therefore it was in inverse proportion to drug loading (range between 5 and 15%). BU release rate increased immediately after irradiation and increased slightly until 90 days of storage. As far as beta-irradiated microspheres are concerned, BU content decreased in a significant way (approximately 3%) only in microspheres containing 10% w/w of BU. Immediately after irradiation, drug release rate in beta-irradiated microspheres increased less than in the corresponding gamma-irradiated microspheres, and it did not change further over the following storage period. BU-loaded microspheres have been shown to be more stable against beta- than gamma-irradiation. AFM revealed that the surface roughness of the irradiated microspheres increases depending on irradiation. As such, if a parameter is quantifiable, it is proposed as a marker of degradation due to ionizing radiation.

Anesthetics, Local↗
PubMed2003

A comparative study between AFM and SEM imaging on human scalp hair.

A comparative study of AFM and SEM imaging of the same area of a human scalp hair has been carried out to determine the similarity and the differences between the two techniques. Sample preparation for SEM analysis requires a metallization step and vacuum exposure, both of which could potentially induce modifications to the surface details. By contrast, AFM is a suitable technique to evaluate any effect resulting from sample manipulation because it can be applied without any specific treatment. AFM analysis demonstrates that sample metallization is responsible for modifications to the surface details of hair, mainly comprising an increase in height of scale steps and of root mean square roughness together with variation in scale profiles. Sample treatments for SEM imaging are in general potentially responsible for surface modifications to the samples involved.

Hair↗
PubMed2002

Synthesis and antinociceptive activity of chimonanthines and pyrrolidinoindoline-type alkaloids.

Hodgkinsine, a trimeric pyrrolidinoindoline type alkaloid, present as a major constituent of Psychotria spp. (Rubiaceae), has shown to produce dose-dependent, naloxone reversible, analgesic effect in thermal models of nociception and in the capsaicin-induced pain. SAR studies have been initiated by synthesizing the three diastereomeric dimers (chimonanthines) (11-13) which were evaluated in vitro and in vivo along with the synthetic intermediates. Strong binding affinities for mu opioid receptors were found for (-)- and (+)-chimonanthine monourethanes (9 and 10), whereas (-)-, (+)- and (meso)-chimonanthine (11-13) and hodgkinsine displayed low affinity. In vivo data have shown that only (+)-chimonanthine (12) and calycosidine resemble the analgesic profile found for hodgkinsine.

Alkaloids↗
PubMed2001

Investigating microbial (micro)colony heterogeneity by vibrational spectroscopy.

Fourier transform infrared and Raman microspectroscopy are currently being developed as new methods for the rapid identification of clinically relevant microorganisms. These methods involve measuring spectra from microcolonies which have been cultured for as little as 6 h, followed by the nonsubjective identification of microorganisms through the use of multivariate statistical analyses. To examine the biological heterogeneity of microorganism growth which is reflected in the spectra, measurements were acquired from various positions within (micro)colonies cultured for 6, 12, and 24 h. The studies reveal that there is little spectral variance in 6-h microcolonies. In contrast, the 12- and 24-h cultures exhibited a significant amount of heterogeneity. Hierarchical cluster analysis of the spectra from the various positions and depths reveals the presence of different layers in the colonies. Further analysis indicates that spectra acquired from the surface of the colonies exhibit higher levels of glycogen than do the deeper layers of the colony. Additionally, the spectra from the deeper layers present with higher RNA levels than the surface layers. Therefore, the 6-h colonies with their limited heterogeneity are more suitable for inclusion in a spectral database to be used for classification purposes. These results also demonstrate that vibrational spectroscopic techniques can be useful tools for studying the nature of colony development and biofilm formation.

Candida albicans↗
PubMed2001

Classification and identification of enterococci: a comparative phenotypic, genotypic, and vibrational spectroscopic study.

Rapid and accurate identification of enterococci at the species level is an essential task in clinical microbiology since these organisms have emerged as one of the leading causes of nosocomial infections worldwide. Vibrational spectroscopic techniques (infrared [IR] and Raman) could provide potential alternatives to conventional typing methods, because they are fast, easy to perform, and economical. We present a comparative study using phenotypic, genotypic, and vibrational spectroscopic techniques for typing a collection of 18 Enterococcus strains comprising six different species. Classification of the bacteria by Fourier transform (FT)-IR spectroscopy in combination with hierarchical cluster analysis revealed discrepancies for certain strains when compared with results obtained from automated phenotypic systems, such as API and MicroScan. Further diagnostic evaluation using genotypic methods-i.e., PCR of the species-specific ligase and glycopeptide resistance genes, which is limited to the identification of only four Enterococcus species and 16S RNA sequencing, the "gold standard" for identification of enterococci-confirmed the results obtained by the FT-IR classification. These results were later reproduced by three different laboratories, using confocal Raman microspectroscopy, FT-IR attenuated total reflectance spectroscopy, and FT-IR microspectroscopy, demonstrating the discriminative capacity and the reproducibility of the technique. It is concluded that vibrational spectroscopic techniques have great potential as routine methods in clinical microbiology.

Bacterial Typing Techniques↗
PubMed2000

FT-IR microspectroscopy for microbiological studies.

In this article we present an infrared microspectroscopic investigation on Candida albicans microcolonies, taken as a model system for studies on other microorganisms. Excellent Fourier transform infrared (FT-IR) absorption spectra from 4000 to 850 cm(-1) have been collected in only 20 s from sampling areas of 100x100 microm(2) in microcolonies, which had been transferred from the agar plate onto zinc selenide (ZnSe) windows. When different regions within a single microcolony were investigated, absorption spectra with important differences in the carbohydrate absorption (from 1200 to 850 cm(-1)) were detected for the cells in the center and in the periphery of the colony. Results obtained on microcolonies grown on solid agar with increasing dextrose concentrations indicated that the observed spectral heterogeneity was related to differences in dextrose uptake, which was lower for the old cells in the center of the colony than for the metabolically active cells at the periphery. Although it is otherwise difficult to quantitatively evaluate the dextrose uptake in a microcolony, FT-IR absorption microspectroscopy offers a new and rapid method for the analysis of this process. The possibility of studying highly absorbing colonies by attenuated total reflection (ATR) by means of an ATR microscope germanium objective is also presented here for the first time. An evaluation of the contact area sampled by this technique is reported with a discussion of the spatial resolution, the quality and the potential of the ATR measurements.

Candida albicans↗
PubMed2000

Development of biocatalysts carrying naphthalene dioxygenase and dihydrodiol dehydrogenase genes inducible in aerobic and anaerobic conditions.

We developed biocatalysts carrying naphthalene dioxygenase and dihydrodiol dehydrogenase genes cloned from plasmid pN3 of Pseudomonas fluoresceins N3 involved in naphthalene degradation, as an alternative approach to the production of hydroxylated compounds by chemical synthesis. Naphthalene dioxygenase is responsible for hydroxylation of the hydrocarbon into the corresponding 1,2-dihydro-1,2-dihydroxy derivative and dihydrodiol dehydrogenase is involved in the subsequent transformation into the 1,2-dihydroxy derivative. The first reaction strictly requires the presence of oxygen, essential for the dioxygenation reaction, while the second one can also be performed in anaerobic conditions that are optimal to avoid the easy oxidation of bioconversion products. Consequently, we constructed biocatalysts carrying the genes responsible for the biotransformation of hydrocarbons, inducible under aerobic and anaerobic conditions. We cloned the dioxygenase gene under its promoter, inducible by salicylic acid and the dihydrodiol dehydrogenase under the Pnar promoter of Escherichia coli, inducible by nitrate, in a nitrogen atmosphere, in order to develop biological systems with the possibility of controlling the expression of the cloned genes by the shift from aerobic to anaerobic conditions. Bioconversion experiments performed in aerobic conditions showed dihydrodiol production and dehydrogenase repression; as soon as cultures were switched to nitrogen, dihydrodiol dehydrogenation with an efficient production of 1,2-dihydroxyderivatives was observed.

Aerobiosis↗
PubMed2000

Effectiveness of rf phase modulation for increasing bunch length in electron storage rings

Aiming at increasing the apparent bunch length and hence the beam lifetime in electron storage rings, rf phase modulation near one parametric resonance has been experimentally investigated. Since the possible benefit of this technique depends greatly on the ring parameters, we studied the effect of such a modulation for different rf parameters on the longitudinal emittance. Theoretical predictions and results of simulations are compared and discussed. It is shown that synchrotron radiation tends to spoil the parametric resonance. In particular, a criterion for island survival has been found.

Journal Article↗
PubMed2000

Central precocious puberty: clinical and imaging aspects.

We review briefly the definition of central precocious puberty (CPP), and discuss early puberty and very early puberty. The association of hypothalamic hamartoma and empty sella with CPP is described. The contribution of new imaging techniques - CT, MRI and ultrasound in the differential diagnosis of CPP is discussed.

Brain Diseases↗
PubMed1999

DNA bending by photolyase in specific and non-specific complexes studied by atomic force microscopy.

Specific and non-specific complexes of DNA and photolyase are visualised by atomic force microscopy. As a substrate for photolyase a 1150 bp DNA restriction fragment was UV-irradiated to produce damaged sites at random positions. Comparison with a 735 bp undamaged DNA fragment made it possible to separate populations of specific and non-specific photolyase complexes on the 1150 bp fragment, relieving the need for highly defined substrates. Thus it was possible to compare DNA bending for specific and non-specific interactions. Non-specific complexes show no significant bending but increased rigidity compared to naked DNA, whereas specific complexes show DNA bending of on average 36 degrees and higher flexibility. A model obtained by docking shows that photolyase can accommodate a 36 degrees bent DNA in the vicinity of the active site.

DNA↗
PubMed1999

Polyphenolic glycosides from african proteaceae

The phytochemical investigation of members of the genus Protea afforded a series of polyphenolic compounds (1-5) that were identified by 1D and 2D NMR experiments. Of these, 2-5 are new compounds. Chemical syntheses of 1-3 were performed in order to confirm the structures and to prepare additional material for biological evaluation.

Journal Article↗