Biomedical subjects

G Antonini

Publications and source records attributed to G Antonini.

At least 19 recordsLinked to original sources

PubMed2006

Pilot installation for the thermo-chemical characterisation of solid wastes.

The increasing production and the large variety of wastes require operators of thermal treatment units to continuously adapt the installations or the functioning parameters to the different physical and chemical properties of the wastes. Usually, the treated waste is encountered in the form of heterogeneous mixtures. The classical tests such as thermogravimetry and calorimetric bomb operate component by component, separately. In addition to this, they can analyse only small quantities of waste at a time (a few grams). These common tests are necessary but insufficient in the global waste analysis in the view further thermal treatment. This paper presents an experimental installation, which was designed and built at the CNRS Science Division, Department of Industrial Methods, Compiègne University of Technology, France. It allows the determination of waste thermal and chemical properties by means of thermal treatment. Also, it is capable of continuously analysing significant quantities of waste (up to 50kg/h) as compared to the classical tests and it can work under various conditions: The installation reproduces the process conditions from incinerators or pyrolysis reactors. It also provides complete information on the kinetics of the waste thermal degradation and on the pollutant emissions. Using different mixtures of components present in the municipal solid waste and also in the reconstituted MSW samples, we defined a series of criteria for characterising waste behaviour during the stages of the main treatment process such as: feeding, devolatilisation/oxidation, advancement, solid residue evacuation, and pollutants emission.

Oxidation-Reduction↗

PubMed2005

Lactoferrin: an important host defence against microbial and viral attack.

The first function attributed to lactoferrin (Lf), an iron binding protein belonging to the non-immune natural defences, was antimicrobial activity that depended on its capacity to sequester iron. Iron-independent microbicidal activities, requiring direct interaction between this cationic protein and microbial surface components, were later demonstrated. Many other anti-microbial and anti-viral functions have since been ascribed to Lf. In mucosal secretions, iron and Lf modulate the motility and aggregation of pathogenic bacteria. Lf inhibits bacterial adhesion on abiotic surfaces through ionic binding to biomaterials, or specific binding to bacterial structures or both. Lf inhibition of bacterial adhesion to host cells requires Lf binding to bacteria and/or host cells. Lf hinders microbial internalization by binding to both glycosaminoglycans and bacterial proteins which can be degraded by Lf-mediated proteolysis. Moreover, Lf internalisation and localisation to the host cell nuclei could modulate bacterial entry into cells through gene regulation. Finally, the capability of Lf to exert antiviral activity, through its binding to host cells and/or viral particles, strengthens the idea that it is an important brick in the mucosal wall, effective against both microbial and viral attacks.

Animals↗

PubMed2004

Intravesical administration of gemcitabine in superficial bladder cancer: a phase I study with pharmacodynamic evaluation.

OBJECTIVE: To determine, in a phase I trial, the local and systemic toxicity and pharmacodynamics of intravesical gemcitabine in patients with superficial bladder cancer. PATIENTS AND METHODS: Twelve patients with histologically confirmed carcinoma localized to the bladder wall (stage T1 or Ta) resistant to previous administration of anticancer drugs and/or of bacille Calmette-Guérin were enrolled. They initially received intravesical gemcitabine starting at 500 mg and increased in 500 mg increments to 2000 mg. Three patients were treated at each dose level. RESULTS: There was no evidence of systemic toxicity and local toxicity was minimal. A pharmacological evaluation showed that gemcitabine was undetectable in plasma and its inactive metabolite (2',2'-difluorodeoxyuridine) was present at a mean (SD) concentration of 1.39 (1.05) mumol/L Deoxycytidine kinase was present in tumour tissue samples, and its activity was 27.3 (12.6) pmol/h/mg tissue; deoxycytidine deaminase activity varied from undetectable to 616 pmol/h/mg tissue. CONCLUSION: Intravesical gemcitabine appears to be well tolerated with no systemic and minimal local toxicity even at the highest dose (2000 mg). A phase II trial of intravesical gemcitabine at 2000 mg given weekly for six consecutive weeks is now in progress in patients with superficial bladder cancer.

Administration, Intravesical↗

PubMed2004

Cerebral atrophy in myotonic dystrophy: a voxel based morphometric study.

Brain involvement in myotonic dystrophy type 1 (DM1) is characterised by cortical atrophy and white matter lesions. We compared the magnetic resonance imaging derived grey matter maps of 22 DM1 patients with those of matched, healthy controls using voxel based morphometry to evaluate the extension of global and regional cortical atrophy in DM1, as well as its relationships with clinical and genetic features. Patients had significantly reduced brain tissue volumes. Grey matter volume was inversely correlated with age; this inverse correlation was significantly stronger in DM1 than in controls. Neither the clinical and genetic characteristics nor white matter lesions were correlated with cortical atrophy. Grey matter atrophy was located mainly in the bilateral frontal and parietal lobes, in the bilateral middle temporal gyrus, and in the left superior temporal and occipital gyrus.

Adult↗

PubMed2003

Autoantibodies to glutamic acid decarboxylase in downbeat nystagmus.

The cause of downbeat nystagmus (DBN) remains undiagnosed in about 40% of patients. This paper reports the presence of antiglutamic acid decarboxylase antibodies (GAD-Ab) in a patient with DBN. Antibodies against GABAergic neurons located in the vestibular complex may induce chemical denervation of the floccular neurons, which normally suppress the peripheral imbalance between vertical semicircular canal systems, thereby causing DBN. Testing for GAD-Ab may be indicated in DBN patients without an identifiable anatomical brain lesion.

Aged↗

PubMed2002

Blood cholesterol and MRI activity in first clinical episode suggestive of multiple sclerosis.

OBJECTIVES: The present study was planned to investigate the relationship between the plasma lipid profile and disease activity in patients with a first clinical episode suggestive of multiple sclerosis (MS). MATERIAL AND METHODS: Eighteen consecutive out-patients underwent a monthly brain magnetic resonance imaging (MRI), blood sample and neurological assessment over 6 months. Blood samples were used to evaluate total cholesterol and triglyceride levels as well as their lipoprotein fractions. Plasma total apolipoprotein E concentration was also determined. RESULTS: We found a significant correlation between the mean number of enhancing lesions and the mean plasma level of both total and low density lipoprotein cholesterol. The total plasma cholesterol level increased on average by 4.4 mg/dl for each enhancing lesion. CONCLUSION: Our preliminary data suggest a potential role of plasma cholesterol level as a biological marker of disease activity after a first demyelinating event. Further studies need, however, to be designed to determine whether the plasma cholesterol level is of practical use in monitoring the disease course.

Acute Disease↗

PubMed2001

Altered circadian cortisol secretion in Alzheimer's disease: clinical and neuroradiological aspects.

We determined circadian salivary cortisol levels in 18 outpatients affected by probable Alzheimer's disease (AD) and looked for a possible correlation with both cognitive impairment and brain CT scan findings. The diagnosis of probable AD was made according to the NINCDS-ADRDA criteria. The severity of cognitive impairment was quantified using the Mini Mental State Examination (MMSE) and the Global Deterioration Scale (GDS). Cortisol levels were measured on saliva samples collected at 08:00 AM and 08:00 PM. For each sample, a duplicate cortisol measurement was performed on 50 microl of saliva by means of a modified commercial radioimmunoassay kit. At the same time, 11 of the 18 AD patients enrolled also underwent a brain CT scan to estimate cerebral atrophy by using linear indexes. The mean value of cortisol levels was significantly higher in AD patients than in controls at both the morning and the evening measurements, and the circadian fluctuation of cortisol was less marked in AD patients than in controls, although this difference did not reach statistical significance. Morning cortisol levels were significantly correlated to both the MMSE and the GDS scores. A significant correlation was also found between morning cortisol levels and all the cerebral atrophy indexes. By contrast, no correlation was observed between evening cortisol levels or cortisol circadian fluctuations and either cognitive impairment or cerebral atrophy. In conclusion, despite the potential biases deriving from the small sample and the limitations of the CT scan study, our results suggest that, in AD patients, hypercortisolemia is correlated with severity of the disease.

Aged↗

PubMed2001

Involvement of bovine lactoferrin metal saturation, sialic acid and protein fragments in the inhibition of rotavirus infection.

Although the antiviral activity of lactoferrin is one of the major biological functions of this iron binding protein, the mechanism of action is still under debate. We have investigated the role of metal binding, of sialic acid and of tryptic fragments of bovine lactoferrin (bLf) in the activity towards rotavirus (intestinal pathogen naked virus) infecting enterocyte-like cells. The antiviral activity of bLf fully saturated with manganese or zinc was slightly decreased compared to that observed for apo- or iron-saturated bLf. The antiviral activity of differently metal-saturated bLf towards rotavirus was exerted during and after the virus attachment step. The removal of sialic acid enhanced the anti-rotavirus activity of bLf. Among all the peptidic fragments obtained by tryptic digestion of bLf and characterised by advanced mass spectrometric methodologies, a large fragment (86-258) and a small peptide (324-329: YLTTLK) were able to inhibit rotavirus even if at lower extent than undigested bLf.

Antiviral Agents↗

PubMed2001

Satellite potentials on EMG: neurophysiologic evidence of axonal transection in MS?

To detect signs of axonal damage in MS, the authors investigated the occurrence in EMG of motor unit action potentials with satellite potentials (SP-MUAP) in the upper limb muscles in 10 consecutive patients with MS with cervical spinal cord demyelinating lesions and 10 control subjects. Subjects' SP-MUAP rate was 0 to 2.5% (median 0%) in the control group, and 0 to 17.5% (median 7.5%) in the MS group (p < 0.01). Motor unit remodeling secondary to axonal transection of spinal motor neurons traversing cervical demyelinating lesions may be hypothesized.

Adult↗

PubMed2001

Dopamine transporter immunoreactivity in peripheral blood lymphocytes in Parkinson's disease.

There is increasing interest in the identification of biological markers for the early diagnosis of Parkinson's disease (PD). Previous studies indicate changes of dopamine content, tyrosine hydroxylase immunoreactivity and dopamine receptors in peripheral blood lymphocytes (PBL) in PD. Here we demonstrate a reduction of dopamine transporter immunoreactivity in PBL in the early clinical stages of the disease. These findings contribute to our understanding of the peripheral dopamine system in PD.

Analysis of Variance↗

PubMed2001

High incidence of hyperandrogenism-related clinical signs in patients with multiple sclerosis.

A mild prevalence of multiple sclerosis (MS) is present in females (2:1). To elucidate the pathogenetic role of sex steroids on the disease, we studied 76 women affected by MS, compared to 50 healthy women (mean age +/- SD, 34.9 +/- 0.9 vs. 33.4 +/- 1.7 years). The menarche was at mean age of 12.3 +/- 0.2 vs. 12.4 +/- 0.2. Interval between menses was 28.0 +/- 0.3 vs 27.8 +/- 0.3 days, with duration of menstrual flow of 5.0 +/- 0.2 vs. 5.0 +/- 0.2 days. Oligo- or amenorrhea was present in 20% of patients and in 16% of controls. Oral contraceptives were assumed by 21% of patients and 34% of controls (n.s.). Premenstrual symptoms were found in 43% of patients and in 46% of controls (n.s.). The incidence of hyperandrogenism (greasy skin, acne and hirsutism), evaluated by a specific questionnaire, was higher and statistically significant in MS patients than in controls (28% vs. 10%, p<0.05). Further studies, including a complete clinical and laboratory evaluation of gonadal function, are necessary in order to clarify whether hyperandrogenism may influence MS disease activity.

Adult↗

PubMed2001

Thrombotic thrombocytopenic purpura: prospective neurologic, neuroimaging and neurophysiologic evaluation.

BACKGROUND AND OBJECTIVES: Neurologic symptoms are present in 60% of patients with thrombotic thrombocytopenic purpura (TTP) on initial examination and ultimately develop in about 90% of cases during the course of the disease. Despite central nervous system involvement being frequent, abnormalities in the brain of patients with TTP are infrequent on neuroimaging (CT/MRI) and neurophysiologic (EEG) evaluation, often reversible and mainly limited to symptomatic stages of the disease. The aim of our study was to establish the value of a complete neurologic screening as part of the work up of TTP. DESIGN AND METHODS: We prospectively evaluated 16 TTP patients, performing serial neurologic, neuroimaging and EEG examinations, independently of the presence of an objective central nervous system involvement. RESULTS: Our study shows that a complete neurologic evaluation is of modest help in improving the diagnosis of TTP, but may be useful for the neurologic management. INTERPRETATION AND CONCLUSIONS: Accurate neuroimaging and, especially, EEG evaluation and monitoring allowed us to identify patients who could benefit from anticonvulsive therapy, avoiding the unnecessary administration of the latter. The prognostic utility of complete neurologic screening in TTP remains to be conclusively demonstrated in larger prospective neurologic studies.

Adolescent↗

PubMed2000

Valine 10 may act as a driver for product release from the active site of human glutathione transferase P1-1.

We have probed the electrophilic binding site (H-site) of human glutathione transferase P1-1 through mutagenesis of two valines, Val 10 and Val 35, into glycine and alanine, respectively. These two residues were previously shown to be the only conformationally variable residues in the H-site and hence may play important roles in cosubstrate recognition and/or product dissociation. Both of these mutant enzymes have been expressed in Escherichia coli and purified and their kinetic properties characterized. The results demonstrate that Val35Ala behaves similarly to wild-type, whereas Val10Gly exhibits a strong decrease of k(cat) and k(cat)/K(m) (cosub) toward two selected cosubstrates: ethacrynic acid and 1-chloro-2,4-dinitrobenzene. Pre-steady-state kinetic analysis of the GSH conjugation with ethacrynic acid shows that both wild-type and Val10Gly mutant enzymes exhibit the same rate-limiting step: the dissociation of product. However, in the Val10Gly mutant there is an increased energetic barrier which renders the dissociation of product more difficult. Similar results are found for the Val10Gly mutant with 1-chloro-2,4-dinitrobenzene as cosubstrate. With this latter cosubstrate, Val 10 also exerts a positive role in the conformational transitions of the ternary complex before the chemical event. Crystallographic analysis of the Val10Gly mutant in complex with the inhibitor S-hexyl-GSH suggests that Val 10 optimally orientates products, thus promoting their exit from the active site.

Alanine↗

PubMed2000

Natural history of cardiac involvement in myotonic dystrophy: correlation with CTG repeats.

The authors prospectively studied the natural course of cardiac involvement and its relationship to cytosine-thymine-guanine (CTG) expansion in 50 patients with myotonic dystrophy who were submitted to periodic cardiovascular EKG and EKG-Holter monitoring during a median follow-up of 56 months. Nineteen patients (38%) developed major EKG changes. CTG length was not correlated with the frequency of EKG abnormalities, but was inversely correlated with the age at onset of EKG abnormalities (p < 0.0001). CTG length influences the timing of cardiac complications in myotonic dystrophy.

Adolescent↗

PubMed2000

Human glutathione transferase T2-2 discloses some evolutionary strategies for optimization of the catalytic activity of glutathione transferases.

Steady state, pre-steady state kinetic experiments, and site-directed mutagenesis have been used to dissect the catalytic mechanism of human glutathione transferase T2-2 with 1-menaphthyl sulfate as co-substrate. This enzyme is close to the ancestral precursor of the more recently evolved glutathione transferases belonging to Alpha, Pi, and Mu classes. The enzyme displays a random kinetic mechanism with very low k(cat) and k(cat)/K(m)((GSH)) values and with a rate-limiting step identified as the product release. The chemical step, which is fast and causes product accumulation before the steady state catalysis, strictly depends on the deprotonation of the bound GSH. Replacement of Arg-107 with Ala dramatically affects the fast phase, indicating that this residue is crucial both in the activation and orientation of GSH in the ternary complex. All pre-steady state and steady state kinetic data were convincingly fit to a kinetic mechanism that reflects a quite primordial catalytic efficiency of this enzyme. It involves two slowly interconverting or not interconverting enzyme populations (or active sites of the dimeric enzyme) both able to bind and activate GSH and strongly inhibited by the product. Only one population or subunit is catalytically competent. The proposed mechanism accounts for the apparent half-site behavior of this enzyme and for the apparent negative cooperativity observed under steady state conditions. These findings also suggest some evolutionary strategies in the glutathione transferase family that have been adopted for the optimization of the catalytic activity, which are mainly based on an increased flexibility of critical protein segments and on an optimal orientation of the substrate.

Arginine↗

PubMed2000

Human glutathione transferase T2-2 discloses some evolutionary strategies for optimization of substrate binding to the active site of glutathione transferases.

Rapid kinetic, spectroscopic, and potentiometric studies have been performed on human Theta class glutathione transferase T2-2 to dissect the mechanism of interaction of this enzyme with its natural substrate GSH. Theta class glutathione transferases are considered to be older than Alpha, Pi, and Mu classes in the evolutionary pathway. As in the more recently evolved GSTs, the activation of GSH in the human Theta enzyme proceeds by a forced deprotonation of the sulfhydryl group (pK(a) = 6.1). The thiol proton is released quantitatively in solution, but above pH 6.5, a protein residue acts as an internal base. Unlike Alpha, Mu, and Pi class isoenzymes, the GSH-binding mechanism occurs via a simple bimolecular reaction with k(on) and k(off) values at least hundred times lower (k(on) = (2.7 +/- 0.8) x 10(4) M(-1) s(-1), k(off) = 36 +/- 9 s(-1), at 37 degrees C). Replacement of Arg-107 by alanine, using site-directed mutagenesis, remarkably increases the pK(a) value of the bound GSH and modifies the substrate binding modality. Y107A mutant enzyme displays a mechanism and rate constants for GSH binding approaching those of Alpha, Mu, and Pi isoenzymes. Comparison of available crystallographic data for all these GSTs reveals an unexpected evolutionary trend in terms of flexibility, which provides a basis for understanding our experimental results.

Arginine↗

PubMed2000

Sensory involvement in spinal-bulbar muscular atrophy (Kennedy's disease).

Spinal-bulbar muscular atrophy (SBMA) is a rare X-linked neuronopathy associated with an abnormal representation of androgen receptors in the nervous system. Standard nerve conduction and histopathological studies have disclosed the involvement of large myelinated sensory fibers in the spinal nerves of SBMA patients. Little is known about the involvement of small sensory neurons and trigeminal nerves. Laser evoked potentials (LEPs) were studied in 6 unrelated patients with SBMA; 5 of these patients also underwent trigeminal reflex recordings, and 3 a sural nerve biopsy. LEPs were markedly abnormal, indicating a dysfunction in pain pathways. Given the sparing of small fibers in the sural nerve specimens, we hypothesize a dysfunction in spinothalamic cells, possibly due to an abnormal representation of the androgen receptors. Except for the jaw-jerk, all the trigeminal reflexes were markedly abnormal. Since the afferents for the jaw-jerk have their cell body within the central nervous system instead of the ganglion, the selective sparing of the jaw-jerk indicates a trigeminal ganglionopathy.

Aged↗

PubMed2000

Hypotaurine protection on cell damage by singlet oxygen.

Singlet oxygen (1O2), generated by irradiating methylene blue, is toxic to melanoma cell cultures. Hypotaurine is known to scavenge efficiently singlet oxygen; the addition of hypotaurine (800 microM) to the medium during irradiation of the dye produces a greater protective effect on cells than taurine added at the same concentration. The assay of some detoxifying enzymatic activities indicate a different mechanism of protection of the two molecules: taurine induces an efficient detoxifying enzymatic action with respect to the control; hypotaurine exerts its effect greatly by specifically scavenging singlet oxygen.

Antioxidants↗