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1.
Int J Med Inform ; 112: 90-98, 2018 04.
Article in English | MEDLINE | ID: mdl-29500027

ABSTRACT

OBJECTIVES: The main purpose of the article is to raise awareness among all the involved stakeholders about the risks and legal implications connected to the development and use of modern telemedicine systems. Particular focus is given to the class of "active" telemedicine systems, that imply a real-world, non-mediated, interaction with the final user. A secondary objective is to give an overview of the European legal framework that applies to these systems, in the effort to avoid defensive medicine practices and fears, which might be a barrier to their broader adoption. METHODS: We leverage on the experience gained during two international telemedicine projects, namely MobiGuide (pilot studies conducted in Spain and Italy) and AP@home (clinical trials enrolled patients in Italy, France, the Netherlands, United Kingdom, Austria and Germany), whose development our group has significantly contributed to in the last 4 years, to create a map of the potential criticalities of active telemedicine systems and comment upon the legal framework that applies to them. Two workshops have been organized in December 2015 and March 2016 where the topic has been discussed in round tables with system developers, researchers, physicians, nurses, legal experts, healthcare economists and administrators. RESULTS: We identified 8 features that generate relevant risks from our example use cases. These features generalize to a broad set of telemedicine applications, and suggest insights on possible risk mitigation strategies. We also discuss the relevant European legal framework that regulate this class of systems, providing pointers to specific norms and highlighting possible liability profiles for involved stakeholders. CONCLUSIONS: Patients are more and more willing to adopt telemedicine systems to improve home care and day-by-day self-management. An essential step towards a broader adoption of these systems consists in increasing their compliance with existing regulations and better defining responsibilities for all the involved stakeholders.


Subject(s)
Delivery of Health Care , Liability, Legal , Patient Safety , Risk Management , Telemedicine/legislation & jurisprudence , Telemedicine/standards , Europe , Humans , Stakeholder Participation
2.
Radiat Environ Biophys ; 54(2): 183-94, 2015 May.
Article in English | MEDLINE | ID: mdl-25636513

ABSTRACT

Very little is known about the influence of environmental radiation on living matter. In principle, important information can be acquired by analysing possible differences between parallel biological systems, one in a reference-radiation environment (RRE) and the other in a low-radiation environment (LRE). We took advantage of the unique opportunity represented by the cell culture facilities at the Gran Sasso National Laboratories of the Istituto Nazionale di Fisica Nucleare, where environment dose rate reduction factors in the underground (LRE), with respect to the external laboratory (RRE), are as follows: 10(3) for neutrons, 10(7) for directly ionizing cosmic rays and 10 for total γ-rays. Chinese hamster V79 cells were cultured for 10 months in both RRE and LRE. At the end of this period, all the cultures were kept in RRE for another 6 months. Changes in the activities of antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT; glutathione peroxidase, GPX) and spontaneous mutation frequency at the hypoxanthine-guanine phosphoribosyl transferase (hprt) locus were investigated. The results obtained suggest that environmental radiation might act as a trigger of defence mechanisms in V79 cells, specifically those in reference conditions, showing a higher degree of defence against endogenous damage as compared to cells grown in a very low-radiation environment. Our findings corroborate the hypothesis that environmental radiation contributes to the development of defence mechanisms in today living organisms/systems.


Subject(s)
Environment , Fibroblasts/radiation effects , Animals , Antioxidants/metabolism , Cell Line , Cricetulus , Dose-Response Relationship, Radiation , Fibroblasts/enzymology , Fibroblasts/metabolism , Gene Expression Regulation/radiation effects , Radiometry
3.
Br J Cancer ; 109(10): 2654-64, 2013 Nov 12.
Article in English | MEDLINE | ID: mdl-24136149

ABSTRACT

BACKGROUND: The DNA-repair gene DNA-dependent kinase catalytic subunit (DNA-PKcs) favours or inhibits carcinogenesis, depending on the cancer type. Its role in human hepatocellular carcinoma (HCC) is unknown. METHODS: DNA-dependent protein kinase catalytic subunit, H2A histone family member X (H2AFX) and heat shock transcription factor-1 (HSF1) levels were assessed by immunohistochemistry and/or immunoblotting and qRT-PCR in a collection of human HCC. Rates of proliferation, apoptosis, microvessel density and genomic instability were also determined. Heat shock factor-1 cDNA or DNA-PKcs-specific siRNA were used to explore the role of both genes in HCC. Activator protein 1 (AP-1) binding to DNA-PKcs promoter was evaluated by chromatin immunoprecipitation. Kaplan-Meier curves and multivariate Cox model were used to study the impact on clinical outcome. RESULTS: Total and phosphorylated DNA-PKcs and H2AFX were upregulated in HCC. Activated DNA-PKcs positively correlated with HCC proliferation, genomic instability and microvessel density, and negatively with apoptosis and patient's survival. Proliferation decline and massive apoptosis followed DNA-PKcs silencing in HCC cell lines. Total and phosphorylated HSF1 protein, mRNA and activity were upregulated in HCC. Mechanistically, we demonstrated that HSF1 induces DNA-PKcs upregulation through the activation of the MAPK/JNK/AP-1 axis. CONCLUSION: DNA-dependent protein kinase catalytic subunit transduces HSF1 effects in HCC cells, and might represent a novel target and prognostic factor in human HCC.


Subject(s)
Biomarkers, Tumor/genetics , Carcinogenesis/genetics , Carcinoma, Hepatocellular/pathology , DNA-Activated Protein Kinase/genetics , Liver Neoplasms/pathology , Nuclear Proteins/genetics , Carcinoma, Hepatocellular/genetics , Cell Line, Tumor , Cell Proliferation , Cell Survival/genetics , DNA-Binding Proteins/physiology , Gene Expression Regulation, Enzymologic , Gene Expression Regulation, Neoplastic , Heat Shock Transcription Factors , Hep G2 Cells , Humans , Liver Neoplasms/genetics , Predictive Value of Tests , Prognosis , Transcription Factors/physiology
4.
Eur Ann Otorhinolaryngol Head Neck Dis ; 129(5): 278-80, 2012 Oct.
Article in English | MEDLINE | ID: mdl-22921301

ABSTRACT

INTRODUCTION: Lobular capillary hemangioma is a frequent benign vascular inflammatory lesion of the skin tissue. It rarely reaches the mucous membrane, and the nasal fossa involvement is exceptional. CASE REPORT: A 68-year-old woman presented with an ulcerous hemorrhagic mass blocking the left nasal fossa, which had appeared a few weeks after a wasp sting in the nose. The insect was evacuated only three weeks after the sting. The clinical and radiological data suggested malignancy. Biopsy under local anesthesia proved non-contributory and was complicated by 1 week's hospitalization for severe nosebleed. Surgical excision under video-endoscopy confirmed diagnosis. At 31 months' follow-up, the patient was free of recurrence. DISCUSSION/CONCLUSION: The pathogeny of lobular capillary hemangioma is uncertain. No previous cases affecting the mucous membrane after insect sting have been reported. Except in the typical contexts of long-term packing or pregnancy, diagnosis can be difficult and misleading. It can mimic a malignant pathology. Its rich vascularization requires caution during biopsy, and the risk of recurrence requires excision to be complete.


Subject(s)
Granuloma, Pyogenic/diagnosis , Granuloma, Pyogenic/etiology , Insect Bites and Stings/complications , Nasal Cavity , Nose Diseases/diagnosis , Nose Diseases/etiology , Wasps , Aged , Animals , Diagnosis, Differential , Female , Follow-Up Studies , Granuloma, Pyogenic/surgery , Humans , Nasal Cavity/diagnostic imaging , Nasal Cavity/pathology , Nasal Cavity/surgery , Nose Diseases/surgery , Radiography , Treatment Outcome
5.
Epidemics ; 4(1): 43-7, 2012 Mar.
Article in English | MEDLINE | ID: mdl-22325013

ABSTRACT

The aim of this paper is to show in explicit detail that, due to the effects of waning and boosting of immunity, an increasing force of infection does not necessarily lead to an increase in the incidence of disease. Under certain conditions, a decrease of the force of infection may in fact lead to an increase of the incidence of disease. Thus we confirm and reinforce the conclusions from Águas et al. (2006), concerning pertussis. We do so, however, in the context of Campylobacter infections in humans deriving from animal reservoirs. For such an externally 'driven' epidemic we can ignore the transmission feedback cycle and treat the force of infection as a parameter. As this parameter is, to a certain extent, under public health control, our findings constitute an important warning: reducing exposure may not necessarily lead to a reduction in the occurrence of clinical illness. In a second part of the paper we relate the model parameters to the available data concerning campylobacteriosis.


Subject(s)
Campylobacter Infections/epidemiology , Campylobacter Infections/immunology , Campylobacter Infections/transmission , Disease Outbreaks/statistics & numerical data , Disease Reservoirs , Humans , Immunity , Life Expectancy , Likelihood Functions , Models, Immunological , Models, Statistical
6.
Hear Res ; 282(1-2): 81-91, 2011 Dec.
Article in English | MEDLINE | ID: mdl-21986211

ABSTRACT

Hearing loss is routinely estimated from the audiogram, even though this measure gives only a rough approximation of hearing. Indeed, cochlear regions functioning poorly, if at all, called dead regions, are not detected by a simple audiogram. To detect cochlear dead regions, additional measurements of psychophysical tuning curves or thresholds in background noise (TEN test) are required. A first aim of this study was to assess the presence of dead regions after impulse noise trauma using psychophysical tuning curves. The procedure we used was based on a compromise between the need to collect reliable estimates of psychophysical tuning curves and the limited time available to obtain these estimates in a hospital setting. Psychophysical tuning curves were measured using simultaneous masking with a 2-alternative forced choice paradigm, where the target was randomly placed in one of the two masker presentations. It is well known that some components of noise-induced hearing loss are reversible. A second aim of this study was to examine the potential recovery of dead regions after acoustic trauma. A third issue addressed in this article was the relationship between noise-induced dead regions and tinnitus. We found that 70% of the subjects had dead regions after noise trauma, while 88% reported tinnitus. Moreover, we found that the extent of dead regions probably diminished in about 50% of subjects, which highlights the ability of the human auditory system to recover from noise-induced hearing loss.


Subject(s)
Auditory Perception , Cochlea/physiopathology , Firearms , Hearing Loss, Noise-Induced/physiopathology , Hearing Loss, Noise-Induced/psychology , Occupational Diseases/physiopathology , Occupational Diseases/psychology , Acoustic Stimulation , Adult , Aged , Audiometry , Auditory Threshold , Cochlea/injuries , Hearing Loss, Noise-Induced/diagnosis , Hearing Loss, Noise-Induced/etiology , Humans , Middle Aged , Military Personnel , Occupational Diseases/diagnosis , Occupational Diseases/etiology , Occupational Exposure , Perceptual Masking , Psychoacoustics , Recovery of Function , Severity of Illness Index , Tinnitus/physiopathology , Tinnitus/psychology , Young Adult
7.
Rev Laryngol Otol Rhinol (Bord) ; 131(3): 213-6, 2010.
Article in French | MEDLINE | ID: mdl-21491774

ABSTRACT

UNLABELLED: We report a case of a parathyroid adenoma during a long term lithium treatment without therapeutic overdose. CASE REPORT: A 73-years-old woman presented a demonstrative biological syndrome with hypercalcemia, elevated parathormone, normal urinary cyclic AMP, normocalciuria. CONCLUSION: This lithium induced hyperparathyroidism differs from the classic primary hyperparathyroidism with parthyroid adenoma where urinary cyclic AMP excretion is elevated and where there is hypercalciuria. Lithium is blocking the negative feedback of calcium on parathormone secretion and stimulates the growth of parathyroid adenoma. Treatment is surgical and consists in adenoma ablation. Calcemia follow up is indicated in patients with long term lithium therapy


Subject(s)
Adenoma/chemically induced , Antipsychotic Agents/adverse effects , Lithium Compounds/adverse effects , Parathyroid Neoplasms/chemically induced , Adenoma/diagnosis , Adenoma/diagnostic imaging , Adenoma/surgery , Aged , Bipolar Disorder/drug therapy , Female , Humans , Hypercalcemia/complications , Hyperparathyroidism/chemically induced , Hyperparathyroidism/complications , Lithium Compounds/administration & dosage , Parathyroid Neoplasms/diagnostic imaging , Parathyroid Neoplasms/surgery , Radionuclide Imaging , Time Factors , Tomography, X-Ray Computed
8.
Gut ; 58(5): 679-87, 2009 May.
Article in English | MEDLINE | ID: mdl-19136513

ABSTRACT

BACKGROUND AND AIMS: Previous studies indicate unrestrained cell cycle progression in liver lesions from hepatocarcinogenesis-susceptible Fisher 344 (F344) rats and a block of G(1)-S transition in corresponding lesions from resistant Brown Norway (BN) rats. Here, the role of the Forkhead box M1B (FOXM1) gene during hepatocarcinogenesis in both rat models and human hepatocellular carcinoma (HCC) was assessed. METHODS AND RESULTS: Levels of FOXM1 and its targets were determined by immunoprecipitation and real-time PCR analyses in rat and human samples. FOXM1 function was investigated by either FOXM1 silencing or overexpression in human HCC cell lines. Activation of FOXM1 and its targets (Aurora Kinose A, Cdc2, cyclin B1, Nek2) occurred earlier and was most pronounced in liver lesions from F344 than BN rats, leading to the highest number of Cdc2-cyclin B1 complexes (implying the highest G(2)-M transition) in F344 rats. In human HCC, the level of FOXM1 progressively increased from surrounding non-tumorous livers to HCC, reaching the highest levels in tumours with poorer prognosis (as defined by patients' length of survival). Furthermore, expression levels of FOXM1 directly correlated with the proliferation index, genomic instability rate and microvessel density, and inversely with apoptosis. FOXM1 upregulation was due to extracellular signal-regulated kinase (ERK) and glioblastoma-associated oncogene 1 (GLI1) combined activity, and its overexpression resulted in increased proliferation and angiogenesis and reduced apoptosis in human HCC cell lines. Conversely, FOXM1 suppression led to decreased ERK activity, reduced proliferation and angiogenesis, and massive apoptosis of human HCC cell lines. CONCLUSIONS: FOXM1 upregulation is associated with the acquisition of a susceptible phenotype in rats and influences human HCC development and prognosis.


Subject(s)
Carcinoma, Hepatocellular/genetics , Extracellular Signal-Regulated MAP Kinases/genetics , Forkhead Transcription Factors/genetics , Liver Neoplasms/genetics , Animals , Carcinoma, Hepatocellular/pathology , Cell Proliferation , Cell Transformation, Neoplastic/genetics , Forkhead Box Protein M1 , Forkhead Transcription Factors/physiology , Gene Expression Regulation, Neoplastic/genetics , Genes, cdc , Genetic Predisposition to Disease/genetics , Liver/pathology , Liver Neoplasms/pathology , Neovascularization, Pathologic/etiology , Rats , Rats, Inbred F344 , Transcriptional Activation , Up-Regulation
9.
Med Trop (Mars) ; 69(6): 549-50, 2009 Dec.
Article in French | MEDLINE | ID: mdl-20099665

ABSTRACT

Fracture of the nose is a frequent injury. Careful management is necessary to avoid not only cosmetic but also functional sequels. Therapeutic modalities are simple and can easily be carried out under local anesthesia.


Subject(s)
Fractures, Closed/diagnosis , Fractures, Closed/surgery , Nose/injuries , Nose/surgery , Anesthesia, Local , Humans
10.
Med Trop (Mars) ; 68(1): 83-6, 2008 Feb.
Article in French | MEDLINE | ID: mdl-18478779

ABSTRACT

Foreign bodies in the nasal fossa are frequent and generally occur in children. In developing countries, access to an ENT specialist can be difficult or impossible. The authors describe several extraction techniques with special emphasis on those best suited to areas with limited access to specialist facilities. Using illustrations, a step-by-step description of the so-called "hook" technique is given. This simple technique allows successful removal of a foreign body from the nasal fossa in almost all cases.


Subject(s)
Foreign Bodies/surgery , Otolaryngology/instrumentation , Surgical Instruments , Developing Countries , Equipment Design , Humans , Nasal Cavity
12.
Ann Otolaryngol Chir Cervicofac ; 119(6): 356-62, 2002 Dec.
Article in French | MEDLINE | ID: mdl-12527846

ABSTRACT

Parotid vascular malformation in the adult is a very rare and benign tumor; only 47 cases were described in the world literature. This vascular malformation, mostly of venous origin is, on the opposite of the clinical, histological and evolution features of parotid hemangiomas in children, which are more frequent. Some clinical and radiological elements are pathognomonic allowing preoperative diagnosis. We present 2 cases of intraparotid venous malformation in adults, and based on an exhaustive study of the world literature discuss frequency, diagnosis and treatment of this disease.


Subject(s)
Arteriovenous Malformations/pathology , Parotid Gland/blood supply , Parotid Gland/surgery , Adult , Arteriovenous Malformations/diagnostic imaging , Arteriovenous Malformations/surgery , Female , Humans , Magnetic Resonance Imaging , Male , Middle Aged , Tomography, X-Ray Computed
13.
J Neurochem ; 78(3): 658-63, 2001 Aug.
Article in English | MEDLINE | ID: mdl-11483669

ABSTRACT

It has recently been suggested that the brain-specific Na+-dependent phosphate inorganic co-transporter (BNPI) is able to support glutamate transport and storage in synaptic vesicles. A procedure for measuring the vesicular pool of glutamate is described and was used to select cell lines according to their glutamate storage capacity. Two cell lines were selected: C6BU-1, with a large intracellular glutamate storage capacity, and NG108-15, devoid of it. Their contents in BNPI mRNA were compared by RT-PCR. We found that both cell lines had BNPI, but in addition C6BU-1 alone expresses the other isoform, DNPI. We also carried out a clonal selection of NG108-15 cells in the presence of the dye Evans blue, a competitive inhibitor of vesicular glutamate transport, very toxic for cells in culture. It was assumed that only those that sequester and eliminate the drug by overexpressing a vesicular glutamate transporter would survive. We found that the NG108-15 clones resistant to Evans blue had an increased storage capacity for glutamate. These cells also up-regulated the BNPI isoform of the phosphate transporter as shown by RT-PCR and northern blot.


Subject(s)
Carrier Proteins/metabolism , Evans Blue/toxicity , Glutamic Acid/metabolism , Symporters , Animals , Carrier Proteins/genetics , Cell Line , Cerebellum/cytology , Coloring Agents/toxicity , Drug Resistance/physiology , Glutamic Acid/chemistry , Protein Isoforms , Reverse Transcriptase Polymerase Chain Reaction , Sodium-Phosphate Cotransporter Proteins , Synaptosomes/metabolism
14.
Arch Neurol ; 58(7): 1133-5, 2001 Jul.
Article in English | MEDLINE | ID: mdl-11448303

ABSTRACT

BACKGROUND: The paraneoplastic syndromes can involve multiple areas of the central nervous system and result in a variety of neurological symptoms. To our knowledge, severe, rapidly progressive, and drug-resistant ballistic-choreic movements have not been previously described as the presenting feature of renal cell carcinoma. PATIENT AND METHODS: A previously healthy 55-year-old man developed limb ballismus and involuntary choreic movements of his face over several weeks. Extensive laboratory, diagnostic, and radiographic studies failed to reveal a cause, until an abnormality on a chest x-ray film prompted a search for a primary neoplasm and a final diagnosis of renal cell carcinoma. High doses of medications traditionally used to treat choreic disorders had no effect on the abnormal movements. A biopsy specimen of the basal ganglia showed focal encephalitic changes but no malignant neoplasm. CONCLUSIONS: Whereas prior cases of paraneoplastic syndromes with chorea have been reported in other forms of cancer, our case was significant because, to our knowledge, renal cell carcinoma has not been previously reported in association with this syndrome. Furthermore, the chorea was categorically resistant to pharmacological treatment, and the movement disorder was the initial and only focal neurological feature of the primary illness.


Subject(s)
Carcinoma, Renal Cell/complications , Carcinoma, Renal Cell/diagnosis , Dyskinesias/etiology , Kidney Neoplasms/complications , Kidney Neoplasms/diagnosis , Paraneoplastic Syndromes/diagnosis , Basal Ganglia/pathology , Biopsy , Carcinoma, Renal Cell/pathology , Chorea/etiology , Diagnosis, Differential , Humans , Kidney Neoplasms/pathology , Male , Middle Aged , Paraneoplastic Syndromes/pathology
15.
FEBS Lett ; 495(1-2): 48-51, 2001 Apr 20.
Article in English | MEDLINE | ID: mdl-11322945

ABSTRACT

The domain structure of hemagglutinin-neuraminidase from Sendai virus (cHN) was investigated by studying the thermal stability in the 20-100 degrees C range. Differential scanning calorimetry evidences two conformational transitions. The first transition is apparently a reversible two-state process, with Tm 48.3 degrees C, and is shifted to 50.1 degrees C in the presence of the substrate analogue 2,3-dehydro-2-deoxy-N-acetyl neuraminic acid, meaning that the substrate binding domain is involved in the transition. The second transition, with apparent Tm 53.2 degrees C, is accompanied by irreversible loss of enzymatic activity of the protein, and the presence of the substrate analogue does not affect the Tm. The data indicate that cHN is composed of two independent folding domains, and that only one domain is involved in the binding of the substrate. Our results suggest that the paramyxovirus neuraminidases have the folding properties of a two-domain protein.


Subject(s)
HN Protein/chemistry , HN Protein/metabolism , N-Acetylneuraminic Acid/analogs & derivatives , Protein Folding , Respirovirus/enzymology , Temperature , Calorimetry , Enzyme Stability/physiology , Fluorescence , N-Acetylneuraminic Acid/chemistry , Peptide Hydrolases/metabolism , Protein Denaturation/physiology , Protein Structure, Tertiary/physiology , Thermodynamics
16.
Brain Res Bull ; 54(4): 363-73, 2001 Mar 01.
Article in English | MEDLINE | ID: mdl-11306187

ABSTRACT

The vesicular acetylcholine transporter (VAChT) and choline acetyltransferase (ChAT) are encoded by genes organized in a single gene locus, and coregulation of the transcription of the two genes has been repeatedly reported in cholinergic tissues. In the present study, different stimuli were used to induce the differentiation of the hybridoma cells NG108-15 and we examined their effects on the modulation of VAChT and ChAT expression at the mRNA and protein levels. All agents upregulated the VAChT and ChAT mRNA levels, but to a different extent. ChAT activity was increased by retinoic acid, dexamethasone, and dibutyrylcyclic AMP (dbcAMP), and a synergistic effect was observed with a combined dexamethasone and dbcAMP treatment. Nonetheless, no changes in the VAChT protein level could be observed, as judged from ligand binding studies as well as from immunochemical detection. Hemicholinium-3-sensitive choline uptake, hemicholinium-3 binding, and acetylcholine content were increased by differentiating agents, with a rank order of potency comparable to their effects on ChAT activity. Prominent changes were observed in the expression of vesicular protein markers, particularly with the associated treatment dexamethasone and dbcAMP. Thus, it appears that although the different stimuli we have been using are able to stimulate neuronal features and activate the transcription of cholinergic genes, they did not contrive to increase the level of VAChT protein in these cells.


Subject(s)
Carrier Proteins/metabolism , Choline O-Acetyltransferase/metabolism , Membrane Transport Proteins , RNA, Messenger/metabolism , Transcription, Genetic/physiology , Vesicular Transport Proteins , Acetylcholine/metabolism , Anti-Inflammatory Agents/pharmacology , Bucladesine/pharmacology , Carrier Proteins/drug effects , Cell Line , Choline/metabolism , Choline O-Acetyltransferase/drug effects , Dexamethasone/pharmacology , Hybridomas/cytology , Hybridomas/drug effects , Hybridomas/metabolism , Keratolytic Agents/pharmacology , Nerve Tissue Proteins/drug effects , Nerve Tissue Proteins/metabolism , Phenotype , RNA, Messenger/drug effects , Transcription, Genetic/drug effects , Tretinoin/pharmacology , Vesicular Acetylcholine Transport Proteins
17.
Neuropharmacology ; 39(11): 2214-21, 2000 Aug 23.
Article in English | MEDLINE | ID: mdl-10963765

ABSTRACT

The glial C6BU-1 cell line, loaded with acetylcholine can release this neurotransmitter. This study was aimed at determining whether disruption of the Golgi-vesicular traffic by brefeldin A would change the acetylcholine release from these cells and affect proteins involved in transmitter release like the 15 kDa proteolipid, common to V-ATPase and mediatophore. Cells were treated for 24 or 36 h with brefeldin A (35.7 microM). The observed changes in cell morphology were typical for brefeldin A treated cells in which protein membrane supply has been stopped. Inhibition of membrane protein supply was confirmed in the present work. Moreover, the 15 kDa proteolipid also decayed to a very low level in the cell membrane fraction. The release of acetylcholine evoked by a calcium challenge and a calcium ionophore, or by electrical pulses decreased markedly. The life time of the release mechanism was of the order of 36 h and half decayed in 24 h. In addition, the electrically evoked release became much shorter. Considering that C6BU-1 cells are able to release large amounts of ACh and their membranes contain a sizeable amount of the 15 kDa proteolipid, these results suggest that this proteolipid may be one of the proteins forming the membrane complex responsible for transmitter release, at least in these cells.


Subject(s)
Acetylcholine/metabolism , Brefeldin A/pharmacology , Membrane Proteins/drug effects , Protein Synthesis Inhibitors/pharmacology , Animals , Electric Stimulation , Glioma , Membrane Proteins/metabolism , Nerve Tissue Proteins/drug effects , Nerve Tissue Proteins/metabolism , Tumor Cells, Cultured/drug effects , Xenopus
18.
J Neurosci Methods ; 91(1-2): 101-7, 1999 Sep 15.
Article in English | MEDLINE | ID: mdl-10522828

ABSTRACT

A chemiluminescent procedure for measuring catecholamines (dopamine, norepinephrine, epinephrine) is described. It is based on the observation that lactoperoxidase catalyses both the oxidation of catecholamines, and the chemiluminescent reaction of luminol with their oxidation product. The assay has been adapted for continuously monitoring the release of catecholamines from adrenergic tissues, from cell suspensions and from cells loaded in culture with dopamine.


Subject(s)
Catecholamines/analysis , Luminescent Measurements , Adrenal Glands/chemistry , Adrenal Glands/metabolism , Animals , Biological Assay , Catecholamines/metabolism , Cell Culture Techniques , Dopamine/pharmacology , Dose-Response Relationship, Drug , Mice , Neostriatum/chemistry , Neostriatum/metabolism , Neurons/drug effects , Neurons/metabolism , Norepinephrine/pharmacology , Organ Culture Techniques
19.
J Neurochem ; 73(4): 1483-91, 1999 Oct.
Article in English | MEDLINE | ID: mdl-10501193

ABSTRACT

Immortalized rat brain endothelial RBE4 cells do not express choline acetyltransferase (ChAT), but they do express an endogenous machinery that enables them to release specifically acetylcholine (ACh) on calcium entry when they have been passively loaded with the neurotransmitter. Indeed, we have previously reported that these cells do not release glutamate or GABA after loading with these transmitters. The present study was set up to engineer stable cell lines producing ACh by transfecting them with an expression vector construct containing the rat ChAT. ChAT transfectants expressed a high level of ChAT activity and accumulated endogenous ACh. We examined evoked ACh release from RBE4 cells using two parallel approaches. First, Ca2+-dependent ACh release induced by a calcium ionophore was followed with a chemiluminescent procedure. We showed that ChAT-transfected cells released the transmitter they had synthesized and accumulated in the presence of an esterase inhibitor. Second, ACh released on an electrical depolarization was detected in real time by a whole-cell voltage-clamped Xenopus myocyte in contact with the cell. Whether cells synthesized ACh or whether they were passively loaded with ACh, electrical stimulation elicited the release of ACh quanta detected as inward synaptic-like currents in the myocyte. Repetitive stimulation elicited a continuous train of responses of decreasing amplitudes, with rare failures. Amplitude analysis showed that the currents peaked at preferential levels, as if they were multiples of an elementary component. Furthermore, we selected an RBE4 transgenic clone exhibiting a high level of ChAT activity to introduce the Torpedo vesicular ACh transporter (VAChT) gene. However, as the expression of ChAT was inactivated in stable VAChT transfectants, the potential influence of VAChT on evoked ACh release could only be studied on cells passively loaded with ACh. VAChT expression modified the pattern of ACh delivery on repetitive electrical stimulation. Stimulation trains evoked several groups of responses interrupted by many failures. The total amount of released ACh and the mean quantal size were not modified. As brain endothelial cells are known as suitable cellular vectors for delivering gene products to the brain, the present results suggest that RBE4 cells genetically modified to produce ACh and intrinsically able to support evoked ACh release may provide a useful tool for improving altered cholinergic function in the CNS.


Subject(s)
Acetylcholine/metabolism , Carrier Proteins/metabolism , Choline O-Acetyltransferase/metabolism , Endothelium, Vascular/physiology , Membrane Transport Proteins , Muscle, Skeletal/physiology , Vesicular Transport Proteins , Animals , Carrier Proteins/genetics , Cell Line, Transformed , Cells, Cultured , Cerebrovascular Circulation , Choline O-Acetyltransferase/genetics , Endothelium, Vascular/cytology , Membrane Potentials , Microcirculation , Neuromuscular Depolarizing Agents/pharmacology , Patch-Clamp Techniques , Piperidines/pharmacology , Rats , Recombinant Proteins/metabolism , Transfection , Vesicular Acetylcholine Transport Proteins , Xenopus laevis
20.
Biochem Biophys Res Commun ; 262(2): 401-5, 1999 Aug 27.
Article in English | MEDLINE | ID: mdl-10462487

ABSTRACT

The 3D structure of paramyxovirus hemagglutinin-neuraminidase has not yet been resolved; however, a theoretical model has been built by using influenza virus and bacterial neuraminidases as template [V. C. Epa (1997) Proteins Struct. Funct. Gen. 29, 264-281]. Two common features of the catalytic mechanism of the neuraminidases of known 3D structure are the anomeric specificity and the involvement of a tyrosine residue in the stabilization of the transition state. These key features have been investigated on the water-soluble ectodomain of the hemagglutinin-neuraminidase from Sendai virus (cHN). The anomeric specificity of the hydrolysis of the substrate by cHN has been investigated by NMR spectroscopy. The immediate product of the reaction was the alpha-anomer, meaning that cHN belongs between glycohydrolases retaining anomeric configuration like influenza virus neuraminidase. Measurements of the UV difference spectrum upon binding of the substrate analogue 2,3-dehydro 2-deossi N-acetyl neuraminic acid indicate the ionization of a tyrosine residue and decreased polarity in the environment of a tryptophan residue. Functional significance of the spectral data was derived from the known structure of influenza neuraminidase, where a tyrosinate ion is involved in the stabilization of the transition-state carbonium ion, and a tryptophan residue is involved in the binding of the acetyl moiety of the substrate. The data give experimental support to the 3D model of paramyxovirus neuraminidase.


Subject(s)
HN Protein/chemistry , Neuraminidase/chemistry , Respirovirus/enzymology , Catalytic Domain , HN Protein/metabolism , Hydrolysis , Isomerism , Models, Molecular , Neuraminic Acids/metabolism , Neuraminidase/metabolism , Nuclear Magnetic Resonance, Biomolecular , Substrate Specificity
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