Biomedical subjects

S Grimaldi

Publications and source records attributed to S Grimaldi.

At least 19 recordsLinked to original sources

PubMed2005

Effects of levodopa oral bolus on the kinematics of the pointing movements in Parkinson's disease patients.

We studied the time-course of a levodopa oral bolus effects on the kinematics of patients affected by a mild akinetic-rigid form of idiopathic Parkinson's disease (PD). Eleven PD patients were evaluated: a) in OFF-state, that is before their first medication or after its withdrawal, b) in ON-state, that is at 1/2, 1, 2, 3, 4, 5, 6, 24, 30 and 48 hours after the administration of 250 mg of levodopa plus 25mg of carbidopa. The main kinematics (i. e.movement time, peak of velocity, peak of acceleration and peak of deceleration) of pointing movements to six target-stimuli placed on the horizontal plane of a table were recorded. Clinical conditions were assessed according to the Motor Examination section of the Unified Parkinson's Disease Rating Scale. The levopoda bolus had stable clinical effects only within the first six hours from its administration. The decline of the clinical response was marked by the changes of peak acceleration whereas other kinematics (i. e. movement time and the peak of velocity) changed also in the late observations (24, 30 and 48 hours after drug intake). The dissociation between the persistent improvement on movement time on peak velocity and the rapid deterioration of levodopa effects on early kinematics (i. e. peak acceleration) could be accounted for by a progressive decline in movement programming.

Administration, Oral↗

PubMed2005

Exposure to 50 Hz electromagnetic radiation promote early maturation and differentiation in newborn rat cerebellar granule neurons.

The wish of this work is the study of the effect of electromagnetic (EMF) radiations at a frequency of 50 Hz on the development of cerebellar granule neurons (CGN). Granule neurons, prepared from newborn rat cerebellum (8 days after birth), were cultured after plate-seeding in the presence of EMF radiations, with the plan of characterizing their cellular and molecular biochemistry, after exposure to the electromagnetic stimulus. Five days challenge to EMF radiations showed, by the cytotoxic glutamate (Glu) pulse test, a 30% decrease of cells survival, while only 5% of mortality was reported for unexposed sample. Moreover, blocking the glutamate receptor (GluR) with the Glu competitor MK-801, no toxicity effect after CGN challenge to EMF radiations and Glu was detected. By patch-clamp recording technique, the Kainate-induced currents from 6 days old exposed CGN exhibited a significant increase with respect to control cells. Western blot and reverse transcription-polymerase chain reaction (RT-PCR) analyses show that EMF exposure of rats CGN, induces a change in both GluRs proteins and mRNAs expression with respect to control. In addition, the use of monoclonal antibody raised against neurofilament protein (NF-200) reveals an increase in NF-200 synthesis in the exposed CGN. All these results indicate that exposure to non-ionizing radiations contribute to a premature expression of GluRs reducing the life span of CGN, leading to a more rapid cell maturation.

Animals↗

PubMed2004

Influence of 50-Hz electromagnetic field on anurian (Xenopus laevis) metamorphosis.

In this study, we show the effect of a 1-mT magnetic field AC at 50 Hz on Xenopus laevis tadpole populations. In the course of a 65-day exposure to the field, tadpole survival showed a small, but significant, decrease (p < 0.0004), together with a striking parallel 6-day shift in tadpole maturation frequency and a significant impairment of their metamorphosis. Particularly, metamorphosis was successful for 85% of individuals in the unirradiated tadpole population and for 45% of individuals in the irradiated tadpole population, respectively.

Animals↗

PubMed2004

Interaction between natural killer and dendritic cells: the role of CD40, CD80 and major histocompatibility complex class i molecules in cytotoxicity induction and interferon-gamma production.

This study focuses on the differential role of CD40 and CD80 costimulatory molecules and major histocompatibility complex class I (MHC-I) antigens in the regulation of the interplay between dendritic cells (DCs) and interleukin (IL)-2-activated human natural killer (NK) lymphocytes. Our data indicate that CD40 and CD80 molecules might play a preferential role in the induction of cytotoxic function but not in the interferon-gamma(IFN-gamma) production by human IL-2-activated NK effectors in the presence of autologous and allogeneic DCs. In addition, a critical role of CD94-dependent MHC-I recognition in the regulation of both IFN-gamma production and target cell lysis was shown in the functional interaction between NK and DCs.

B7-1 Antigen↗

PubMed2004

SNOM and AFM microscopy techniques to study the effect of non-ionizing radiation on the morphological and biochemical properties of human keratinocytes cell line (HaCaT).

In this study we have employed atomic force microscopy (AFM) and scanning near-field optical microscopy (SNOM) techniques to study the effect of the interaction between human keratinocytes (HaCaT) and electromagnetic fields at low frequency. HaCaT cells were exposed to a sinusoidal magnetic field at a density of 50 Hz, 1 mT. AFM analysis revealed modification in shape and morphology in exposed cells with an increase in the areas of adhesion between cells. This latter finding was confirmed by SNOM indirect immunofluorescence analysis performed with a fluorescent antibody against the adhesion marker beta4 integrin, which revealed an increase of beta4 integrin segregation in the cell membrane of 50-Hz exposed cells, suggesting that a higher percentage of these cells shows a modified pattern of this adhesion marker.

Cell Adhesion↗

PubMed2003

Asymmetric binding of the high-affinity Q(H)(*)(-) ubisemiquinone in quinol oxidase (bo3) from Escherichia coli studied by multifrequency electron paramagnetic resonance spectroscopy.

Ubiquinone-2 (UQ-2) selectively labeled with (13)C (I =(1)/(2)) at either the position 1- or the 4-carbonyl carbon is incorporated into the ubiquinol oxidase bo(3) from Escherichia coli in which the native quinone (UQ-8) has been previously removed. The resulting stabilized anion radical in the high-affinity quinone-binding site (Q(H)(*)(-)) is investigated using multifrequency (9, 34, and 94 GHz) electron paramagnetic resonance (EPR) spectroscopy. The corresponding spectra reveal dramatic differences in (13)C hyperfine couplings indicating a strongly asymmetric spin density distribution over the quinone headgroup. By comparison with previous results on labeled ubisemiquinones in proteins as well as in organic solvents, it is concluded that Q(H)(*)(-) is most probably bound to the protein via a one-sided hydrogen bond or a strongly asymmetric hydrogen-bonding network. This observation is discussed with regard to the function of Q(H) in the enzyme and contrasted with the information available on other protein-bound semiquinone radicals.

Binding Sites↗

PubMed2001

Mutations in both sides of the photosystem I reaction center identify the phylloquinone observed by electron paramagnetic resonance spectroscopy.

The core of photosystem I (PS1) is composed of the two related integral membrane polypeptides, PsaA and PsaB, which bind two symmetrical branches of cofactors, each consisting of two chlorophylls and a phylloquinone, that potentially link the primary electron donor and the tertiary acceptor. In an effort to identify amino acid residues near the phylloquinone binding sites, all tryptophans and histidines that are conserved between PsaA and PsaB in the region of the 10th and 11th transmembrane alpha-helices were mutated in Chlamydomonas reinhardtii. The mutant PS1 reaction centers appear to assemble normally and possess photochemical activity. An electron paramagnetic resonance (EPR) signal attributed to the phylloquinone anion radical (A(1)(-)) can be observed either transiently or after illumination of reaction centers with pre-reduced iron-sulfur clusters. Mutation of PsaA-Trp(693) to Phe resulted in an inability to photo-accumulate A(1)(-), whereas mutation of the analogous tryptophan in PsaB (PsaB-Trp(673)) did not produce this effect. The PsaA-W693F mutation also produced spectral changes in the time-resolved EPR spectrum of the P(700)(+) A(1)(-) radical pair, whereas the analogous mutation in PsaB had no observable effect. These observations indicate that the A(1)(-) phylloquinone radical observed by EPR occupies the phylloquinone-binding site containing PsaA-Trp(693). However, mutation of either tryptophan accelerated charge recombination from the terminal Fe-S clusters.

Animals↗

PubMed2001

QH*- ubisemiquinone radical in the bo3-type ubiquinol oxidase studied by pulsed electron paramagnetic resonance and hyperfine sublevel correlation spectroscopy.

The high-affinity QH ubiquinone-binding site in the bo(3) ubiquinol oxidase from Escherichia coli has been characterized by an investigation of the native ubiquinone radical anion QH(*-) by pulsed electron paramagnetic resonance (EPR) spectroscopy. One- and two-dimensional electron spin-echo envelope modulation (ESEEM) spectra reveal strong interactions of the unpaired electron of QH(*-) with a nitrogen nucleus from the surrounding protein matrix. From analysis of the experimental data, the (14)N nuclear quadrupolar parameters have been determined: kappa = e(2)qQ/4h = 0.93 MHz and eta = 0.50. This assignment is confirmed by hyperfine sublevel correlation (HYSCORE) spectroscopy. On the basis of a comparison of these data with those obtained previously for other membrane-protein bound semiquinone radicals and model systems, this nucleus is assigned to a protein backbone nitrogen. This result is discussed with regard to the location and potential function of QH in the enzyme.

Anions↗

PubMed2001

Grasp with hand and mouth: a kinematic study on healthy subjects.

Neurons involved in grasp preparation with hand and mouth were previously recorded in the premotor cortex of monkey. The aim of the present kinematic study was to determine whether a unique planning underlies the act of grasping with hand and mouth in humans as well. In a set of four experiments, healthy subjects reached and grasped with the hand an object of different size while opening the mouth (experiments 1 and 3), or extending the other forearm (experiment 4), or the fingers of the other hand (experiment 5). In a subsequent set of three experiments, subjects grasped an object of different size with the mouth, while opening the fingers of the right hand (experiments 6-8). The initial kinematics of mouth and finger opening, but not of forearm extension, was affected by the size of the grasped object congruently with the size effect on initial grasp kinematics. This effect was due neither to visual presentation of the object, without the successive grasp motor act (experiment 2) nor to synchronism between finger and mouth opening (experiments 3, 7, and 8). In experiment 9 subjects grasped with the right hand an object of different size while pronouncing a syllable printed on the target. Mouth opening and sound production were affected by the grasped object size. The results of the present study are discussed according to the notion that in an action each motor act is prepared before the beginning of the motor sequence. Double grasp preparation can be used for successive motor acts on the same object as, for example, grasping food with the hand and ingesting it after bringing it to the mouth. We speculate that the circuits involved in double grasp preparation might have been the neural substrate where hand motor patterns used as primitive communication signs were transferred to mouth articulation system. This is in accordance with the hypothesis that Broca's area derives phylogenetically from the monkey premotor area where hand movements are controlled.

Adult↗

PubMed2000

Three dimensional (3D) analysis of the morphological changes induced by 50 Hz magnetic field exposure on human lymphoblastoid cells (Raji).

Human Raji B lymphoid cells after exposure for 64 h to a 1 mT (rms) 50 Hz sinusoidal magnetic field showed a reorganization of membrane and cytoskeletal components. Atomic force microscopy in air revealed several modifications in 80% of the exposed cells, such as loss of microvilli-like structures followed by progressive appearance of membrane introflections. This change in plasma membrane morphology was also accompanied by a different actin distribution, as detected by phalloidin fluorescence. These observations support our previous hypothesis that electric and magnetic fields may modify the plasma membrane structure.

B-Lymphocytes↗

PubMed1999

Cocaine potentiates the switch between latency and replication of Epstein-Barr virus in Raji cells.

This paper shows that cocaine amplifies Epstein-Barr virus (EBV) reactivation in Raji cells. Its effect on early viral protein synthesis was maximal when it was added with 12-O-tetradecanoyl phorbol-13-acetate (TPA) plus n-butyrate, but nil when added alone. The enhancing effect of cocaine on early replicative stages of latent EBV was associated with an increase of Ca(2+) mobilization induced by the drug and with an induction of cellular protein phosphorylation in chemicals and cocaine-treated Raji cells. Cocaine also acted synergistically with TPA and n-butyrate to induce Z Epstein-Barr replication activator (ZEBRA), a nuclear phosphoprotein responsible for the activation of early viral gene expression. These findings provide the first evidence that cocaine may represent an important co-factor in the reactivation of early stages of latent EBV infection.

Biological Transport↗

PubMed1999

Tacrolimus suppresses tumour necrosis factor-alpha and protects against splanchnic artery occlusion shock.

1. Tumour necrosis factor (TNF-alpha) is a pleiotropic cytokine which is deeply involved in the pathogenesis of splanchnic artery occlusion (SAO) shock. Tacrolimus, formerly known as FK506, is a macrolide antibiotic, that blocks the transcription of several proinflammatory cytokines including TNF-alpha. 2. Male anaesthetized rats were subjected to clamping of the splanchnic arteries for 45 min. This surgical procedure resulted in an irreversible state of shock (SAO shock). Sham operated animals were used as controls. SAO shocked rats had a decreased survival rate (0% at 4 h of reperfusion, while sham shocked rats survived more than 4 h), enhanced serum TNF-alpha concentrations (415+/-12 U ml(-1)), decreased mean arterial blood pressure (MAP), leukopenia and increased ileal leukocyte accumulation studied by means of myeloperoxidase activity (MPO=7.5+/-0.3 U g(-1) tissue). Moreover aortic rings from shocked rats showed a marked hyporeactivity to phenylephrine (PE, 1 nM - 10 microM), reduced responsiveness to acetylcholine (ACh, 10 nM - 10 microM) and increased staining for intercellular adhesion molecule-1 (ICAM-1). Furthermore increased mRNA for TNF-alpha was observed in peritoneal macrophages of SAO shocked rats. 3. Tacrolimus (100 microg kg(-1), 5 min after splanchnic arteries occlusion) increased survival rate (SAO + Tacrolimus = 100% at 4 h of reperfusion), reverted the marked hypotension, reduced serum TNF-alpha (15+/-3 U ml(-1)), ameliorated leukopenia, reduced ileal MPO (0.9+/-0.01 U g(-1) tissue), restored to control values the hyporeactivity to PE. improved the reduced responsiveness to ACh and blunted the enhanced immunostaining for ICAM-1 in the aorta. Finally tacrolimus suppressed cytokine mRNA levels in peritoneal macrophages. 4. The data suggest that tacrolimus may represent a new therapeutic approach in circulatory shock.

Animals↗

PubMed1997

Effect of extremely low frequency (ELF) magnetic field exposure on morphological and biophysical properties of human lymphoid cell line (Raji).

Human B lymphoid cells (Raji) were exposed for 72 h to a 50 Hz sinusoidal magnetic field at a density of 2 milliTesla (rms). The results of exposure showed a decrease in membrane fluidity as detected by Laurdan emission spectroscopy and DPH fluorescence polarization. Field exposure also resulted in a reorganization of cytoskeletal components. Scanning electron microscopy (SEM) revealed a loss of microvilli in the exposed cells. This change in plasma membrane morphology was accompanied by a different actin distribution, as detected by phalloidin fluorescence. We also present evidence that EMF exposure of Raji cells can interfere with protein phosphorylation. Our observations confirm the hypothesis that electric and magnetic fields may modify the plasma membrane structure and interfere with the initiation of the signal cascade pathways.

Actins↗

PubMed1997

Red blood cells mediated delivery of 9-(2-phosphonylmethoxyethyl)adenine to primary macrophages: efficiency metabolism and activity against human immunodeficiency virus or herpes simplex virus.

Red blood cells (RBC) may act as selective carriers of drugs to macrophages, an important reservoir of viruses such as human immunodeficiency virus (HIV) and herpes simplex virus type 1 (HSV-1). We therefore assessed the incorporation of 9-(2-phosphonylmethoxyethyl)adenine (PMEA), a potent inhibitor of HIV and HSV-1) into RBC, its delivery to macrophages and its activity against HIV or HSV-1. Loading of PMEA in artificially aged opsonized RBC affords significant levels of intracellular PMEA. RBC metabolize PMEA to its active congener PMEA-diphosphate, although with low efficiency. Exposure of macrophages to RBC-encapsulated PMEA inhibits the replication of both HIV and HSV-1 (about 90% inhibition at the highest RBC:macrophages ratios) even if RBC were removed before virus challenge. By contrast, the antiviral activity of free PMEA removed before virus challenge was irrelevant at concentrations up to 150-fold higher than the 50% effective concentration (EC50). Finally, the antiviral effect of RBC-encapsulated PMEA correlates with PMEA levels in macrophages about 500-fold higher than those achieved by free PMEA (at concentrations 10-fold higher than the EC50). The efficacy of RBC-mediated delivery to macrophages of PMEA (and perhaps of compounds with shorter intracellular half-lives) warrants further studies in infectious diseases involving phagocytizing cells as main targets of the pathogen.

Adenine↗

PubMed1997

Exposure to a 50 Hz electromagnetic field induces activation of the Epstein-Barr virus genome in latently infected human lymphoid cells.

The EBV genome in latently infected lymphoid cells offers an opportunity to follow effects on the transcriptional and translational product clearly distinguishable from those of the host cell genome. Exposure of Akata cells, a human lymphoid cell line latently infected by the EBV genome, to a 50 Hz EMF resulted in an increased number of cells expressing the virus early antigens. This finding provides additional evidence that DNA can be modulated by a magnetic field.

Antigens, Viral↗

PubMed1996

Role of membrane fluidity in Epstein Barr virus (EBV) infectivity on Akata cell line.

Infection of Epstein Barr virus (EBV) to its host cells is initiated by the attachment of the glycoprotein gp 350/220 to the CR2 molecule. We used the sensitivity at the polar environment of the fluorescent probe Laurdan to study the membrane viscosity distribution from single leaving cells on two lymphoid cell lines Raji and Akata. Lipid analysis on both cells line demonstrated a lower cholesterol to phospholipid molar ratio on Akata than Raji cells. Cell fluidity analysis by Laurdan generalized emission polarization (GP) or by DPH polarization, indicated that membrane viscosity of Akata was lower than Raji cells. This difference was correlated to the increased susceptibility of Akata cells in expressing EBV early antigens (EA) after EBV superinfection.

2-Naphthylamine↗

PubMed1994

Hoechst 33258 staining for detecting mycoplasma contamination in cell cultures: a method for reducing fluorescence photobleaching.

DNA fluorochrome staining with Hoechst 33258 bisbenzimide is commonly used for detection of mycoplasma contamination in cell cultures. Photobleaching of Hoechst 33258 is pronounced under the conditions of intense illumination, high magnification and resolution required for detection of mycoplasmas. To reduce photobleaching we investigated the effects of some antioxidant molecules, p-phenylenediamine (PPD), n-propyl gallate (NPG) and 1,4-diazabicyclo(2,2,2)octane (DABCO), which are known to reduce the fading rate of fluorescein. Mycoplasma-contaminated cell monolayers were stained with Hoechst 33258 and mounted in glycerol containing different amounts of antioxidant additives. The cells were examined in an epifluorescence microscope, and the emitted light intensity was recorded. Results showed that PPD and, to a lower degree, NPG, retarded the photobleaching of Hoechst 33258-stained cells, whereas DABCO was not effective. However, fluorescence half-life was increased about three-fold by NPG and almost 20-fold by PPD. The rate of fluorescence fading of Hoechst 33258 can therefore be retarded by PPD, with obvious advantages for reading and photographic recording of results.

3T3 Cells↗

PubMed1993

EBV membrane receptor (CR2) is phosphorylated by protein kinase C (PKC) in the early stages of virus entry into lymphoblastoid cells line (Raji).

Labeling the EBV membrane with octadecylrhodamine-b-chloride (R18) we were able to monitor spectrofluorometrically the early events of EBV fusion, under conditions in which we could affect PKC activity. Binding of EBV to Raji cells induces PKC translocation from the cytosol to the plasma membrane and 32P incorporation into its cellular receptor CR2. CR2 phosphorylation is completely inhibited when cells are preincubated with the PKC inhibitor calphostin c. This treatment also generates a strong inhibition of EBV fusion. Taken together this result suggests a key role of CR2 phosphorylation in the EBV entry into Raji cells.

Adenosine Triphosphate↗