Search PubMed⌕ Search

Biomedical subjects

R Rinaldi

Publications and source records attributed to R Rinaldi.

At least 19 recordsLinked to original sources
PubMed2006

Charge transport in disordered films of non-redox proteins.

Electrical conduction in solid state disordered multilayers of non-redox proteins is demonstrated by two-terminal transport experiments at the nanoscale and by scanning tunneling microscopy (STM/STS experiments). We also show that the conduction of the biomolecular films can be modulated by means of a gate field. These results may lead to the implementation of protein-based three-terminal nanodevices and open important new perspectives for a wide range of bioelectronic/biosensing applications.

Animals↗
PubMed2006

De novo pure 12q22q24.33 duplication: first report of a case with mental retardation, ADHD, and Dandy-Walker malformation.

We present a patient with a de novo 12q nonmosaic pure duplication characterized by multiple minor anomalies and Dandy-Walker malformation. A neurological and behavioral assessment revealed psychomotor retardation and attention deficit/hyperactivity disorder (ADHD), with neurobehavioral abnormalities (auto- and heteroaggressive behavior). Fluoxetine therapy in this case markedly improved the neurobehavioral profile, with a decreased level of aggression. To define the extension of the duplicated region, we performed FISH analyses by using YAC probes. The analyses revealed a tandem duplication of the 12q22q24.33 region, with the proximal breakpoint located between 96.5 and 97.6 cM and the distal one between 154 and 161 cM. This is the first case of pure de novo duplication involving the 12q22q24.33 region. To better define the clinical phenotype associated with 12q partial duplication, we compared our case with the four patients with similar pure duplications previously described.

Abnormalities, Multiple↗
PubMed2005

Study of the surface morphology of a cholesteryl tethering system for lipidic bilayers.

The immobilization of functional molecules embedded in lipidic membranes onto inorganic substrates is of great interest for numerous applications in the fields of biosensors and biomaterials. We report on the preparation and the morphological characterization of a tethering system for lipidic bilayers, which is based on cholesteryl derivatives deposited on hydrophilic surfaces by self-assembling and microcontact printing techniques. The investigation of the structural properties of the realized films by atomic, lateral, and surface potential microscopy allowed us to assess the high quality of the realized cholesteryl layers.

Cholesterol↗
PubMed2005

Retention of nativelike conformation by proteins embedded in high external electric fields.

In this Communication, we show that proteins embedded in high external electric fields are capable of retaining a nativelike fold pattern. We have tested the metalloprotein azurin, immobilized onto SiO2 substrates in air with proper electrode configuration, by applying static fields up to 10(6)-10(7) Vm. The effects on the conformational properties of protein molecules have been determined by means of intrinsic fluorescence measurements. Experimental results indicate that no significant field-induced conformational alteration occurs. Such results are also discussed and supported by theoretical predictions of the inner protein fields.

Journal Article↗
PubMed2005

Epidemiology of status epilepticus in a rural area of northern Italy: a 2-year population-based study.

We performed a 2-year population-based study on status epilepticus (SE) in adults in the rural area of Lugo di Romagna, northern Italy, to verify whether an area of low-level urbanization has a lower risk of occurrence of SE (as recently suggested), different clinical features and short-term prognosis than areas of high-level urbanization. We found crude and age- and sex-adjusted annual incidence rates of SE of 16.5/100 000 and 11.6/100 000, respectively. In patients under 60 years crude incidence was 2.9/100 000 and in the elderly (>/=60 years) 38.6/100 000. Acute symptomatic SE accounted for 30% and a cerebrovascular pathology was the most frequently associated etiologic condition (60%). A history of seizures was reported in 41% of patients. The first therapeutic intervention was mainly benzodiazepines (lorazepam 46%; diazepam 33%). The 30-day case fatality was 7%. We observed that the adult population of an area with a low level of urbanization has the same risk for SE, clinical features and short-term prognosis as European urban areas. The only contrasting result is the 30-day case fatality of 7% against the 39% found in the other Italian study (Bologna), despite the similarity of the SE features in these two areas of the same region. We infer that the short-term prognosis of SE could also be considerably influenced by differences in health service organization (and hence management) possibly due to different levels of urbanization.

Adult↗
PubMed2004

Solid state protein monolayers: morphological, conformational, and functional properties.

We have studied the morphological, conformational, and electron-transfer (ET) function of the metalloprotein azurin in the solid state, by a combination of physical investigation methods, namely atomic force microscopy, intrinsic fluorescence spectroscopy, and scanning tunneling microscopy. We demonstrate that a "solid state protein film" maintains its nativelike conformation and ET function, even after removal of the aqueous solvent.

Adsorption↗
PubMed2004

Formation and characterization of glutamate dehydrogenase monolayers on silicon supports.

In this paper we have tested two different procedures (the "three-step" and the "four-step" procedures) for the covalent immobilization of glutamate dehydrogenase (GDH) onto silicon supports. Atomic force microscopy (AFM), Fourier-transform infrared spectroscopy (FT-IR), fluorescence spectroscopy and an enzymatic assay were used to probe the structure and activity of the immobilized enzyme. Our results demonstrate that coupling through the "three-step" procedure does not significantly affect either the fold pattern or the activity of the enzyme, suggesting that this method could be ideally suited to the development of high quality monolayers for use in enzyme-based planar biosensors.

Biosensing Techniques↗
PubMed2004

Structural stability study of protein monolayers in air.

The assessment of the folding and of the structural stability of a protein in air, upon immobilization in the solid state, represents a critical point from both a fundamental point of view and for the development of solid state nanobioelectronics. The recent demonstrations by Rinaldi et al. [R. Rinaldi et al., Adv. Mater. 14, 1453 (2002); Appl. Phys. Lett. 82, 472 (2003); Ann. (N.Y.) Acad. Sci. 1006, 187 (2003)] of protein-based solid state devices and transistors working in air have raised an intriguing question about the behavior of a biomolecule under nonphysiological conditions. The operation principle of the realized devices is based on the physiological electron transfer function of the metalloprotein azurin. This means that azurin should retain its shape and functionality also in the solid state when utilized in air and at room temperature. In this Brief Report, we prove this claim by analyzing the conformational state of the azurin monolayers developed for such devices by means of intrinsic fluorescence spectroscopy. We show that the immobilization of azurins in the solid state under nonliquid conditions, by means of a specific chemisorption process, does not necessarily lead to protein denaturation. This result is of great importance because it opens up interesting perspectives for the development of solid state hybrid nanodevices for electronic applications requiring nonliquid environments.

Adsorption↗
PubMed2004

Self-assembling of proteins and enzymes at nanoscale for biodevice applications.

Different nanotechnological strategies have been selected to implement biomolecular devices following a bottom-up or top-down approach depending on the biomolecule and on its functionality. Biomolecules have particular functionality and self-assembling capabilities that can be exploited for the implementation of both bioelectronic devices and multipurpose engineered biosurfaces. Surface preparation with supramolecular methods and microcontact printing have been developed and optimised to realise suitable functionalised surfaces. These surfaces can be used to link metalloproteins and enzymes for the implementation of nanobioelectronic devices and planar biosensors or to bind cells in order to promote their growth along predefined tracks and grooves. Some possible applications of these biosurfaces are shown and discussed. Results are presented for the realisation of a biomolecular nanodevice working in air based on the metalloprotein azurin immobilised in the solid state, the formation and characterisation of functional glutamate Dehydrogenase monolayers for nanobiosensing applications, the results of soft lithography processes on azurin for biosensor implementation, and the development of physiological self-assembled patterns of laminin-1 for cell culture applications and hybrid devices.

Journal Article↗
PubMed2004

Ambipolar transistors based on azurin proteins.

A new type of transistor is presented. It is realised by using a metalloprotein; namely, azurin. Thanks to their natural functional characteristics, which involve inter- and intramolecular electron transfer, metalloproteins are good candidates for biomolecular nanoelectronics. The implementation of a prototype of protein transistor operating in air and in the solid state based on self-organised films of azurins is reported. Experimental current-voltage characteristics are shown. The new device presents an ambipolar behaviour as the gate bias voltage is changed. Exploiting this peculiar characteristic, a fully integrated logic gate which can be a good starting point for a new class of nanoelectronics devices has been realised.

Journal Article↗
PubMed2003

Intrinsic fluorescence spectroscopy of glutamate dehydrogenase: Integrated behavior and deconvolution analysis.

In this paper, we present a deconvolution method aimed at spectrally resolving the broad fluorescence spectra of proteins, namely, of the enzyme bovine liver glutamate dehydrogenase (GDH). The analytical procedure is based on the deconvolution of the emission spectra into three distinct Gaussian fluorescing bands G(j). The relative changes of the G(j) parameters are directly related to the conformational changes of the enzyme, and provide interesting information about the fluorescence dynamics of the individual emitting contributions. Our deconvolution method results in an excellent fitting of all the spectra obtained with GDH in a number of experimental conditions (various conformational states of the protein) and describes very well the dynamics of a variety of phenomena, such as the dependence of hexamers association on protein concentration, the dynamics of thermal denaturation, and the interaction process between the enzyme and external quenchers. The investigation was carried out by means of different optical experiments, i.e., native enzyme fluorescence, thermal-induced unfolding, and fluorescence quenching studies, utilizing both the analysis of the "average" behavior of the enzyme and the proposed deconvolution approach.

Animals↗
PubMed2003

Deep neck infection: a present-day complication. A retrospective review of 83 cases (1998-2001).

Deep neck infections are less and less frequent today than in the past. Nevertheless, their complications are often life-threatening. The present study reviews the experience of the Department of Otolaryngology and Head and Neck Surgery of Padua with deep neck infections during the period from 1998 to 2001. Eighty-three patients (55 males and 28 females) were retrospectively considered. The site of origin of deep neck infection was identified in 76 patients (91%). The most common cause was dental infection, occurring in 35 cases (42%). In 12 cases (14%) deep neck infection was a complication of oropharyngeal infection. The relatively high incidence of Peptostreptococcus sp, Streptococcus viridans, Streptococcus intermedius and constellatus isolation was consistent with the high rate of odontogenic cases. Surgery was advocated as the treatment for any infection of the deep neck spaces. The recent series has demonstrated that medical treatment did not seem to increase complication rates or mortality. Our tailored approach (medical or medical and surgical) based on clinical and radiological evidence was successful in 97% of the patients.

Adolescent↗
PubMed2003

Cytogenetic and molecular characterization of a de novo 4q24qter duplication and correlation to the associated phenotype.

We report on a newborn with severe psychomotor retardation, minor anomalies, congenital heart defects, thumb and urogenital abnormalities. Cytogenetic analysis showed a 4q24qter duplication, never described before, as the result of a de novo t(4;14). The extension of the duplicated 4q region was defined by FISH using YAC probes. The breakpoint was localized between 106.3cM (YAC 800f2, D4S1572) and 111 cM (YAC 744e4, D4S1564). Comparing our patient with those previously reported in literature, we observed some features mature frequently reported in these patients: psychomotor retardation, retromicrognathia, low set and/or malformed ears and some more specific traits: congenital cardiac defects, hypoplastic thumb and urogenital abnormalities.

Abnormalities, Multiple↗
PubMed2003

Optical characterization of glutamate dehydrogenase monolayers chemisorbed on SiO2.

This paper describes the formation of glutamate dehydrogenase monolayers on silicon dioxide, and their characterization by means of physical techniques, i.e., fluorescence spectroscopy and Fourier-transform infrared spectroscopy. Detailed investigations of the intrinsic stability of native proteins in solution were carried out to elucidate the occurrence of conformational changes induced by the immobilization procedure. The enzyme monolayers were deposited on SiO2 after preexposing silicon surfaces to 3-aminopropyltriethoxysilane and reacting the silylated surfaces with glutaric dialdehyde. The optical characterization demonstrates that the immobilization does not interfere with the fold pattern of the native enzyme. In addition, fluorescence spectroscopy, thermal denaturation, and quenching studies performed on the enzyme in solution well describe the folding and unfolding properties of glutamate dehydrogenase. The photophysical studies reported here are relevant for nanobioelectronics applications requiring protein immobilization on a chip.

Biophysical Phenomena↗
PubMed2003

Accuracy of ICD-9 codes in identifying ischemic stroke in the General Hospital of Lugo di Romagna (Italy).

We assessed the sensitivity and the positive predictive value (PPV) of the ICD-9 codes in identifying ischemic strokes. The study involved the cross-sectional comparison between patients with an ischemic stroke diagnosis made by neurologists and patients with the 434 or 436 discharge codes. Sensitivity of the codes (all diagnostic levels and first level respectively) was 82% and 76%; PPV: 71% and 76%. The annual crude incidence of ischemic stroke was 2.62 per 1000 based on verified strokes and 3.03 per 1000 based on 434 or 436 coded medical records (at all diagnostic levels). Thirty-day case fatality ratio was 22.3% in verified strokes and 36.8% among patients diagnosed with codes 434 or 436 but without stroke (all levels). Our results disclosed inaccuracy in use of the ICD-9 codes in the diagnosis of ischemic stroke in the general hospital of Lugo di Romagna, Ravenna Province, Italy. The misdiagnosis of patients could be influenced by the degree of severity of clinical features. Epidemiological data and cost-analysis forecasts based only on the ICD-9 system must be considered with caution.

Cerebrovascular Disorders↗