Biomedical subjects

M Malo

Publications and source records attributed to M Malo.

10 recordsLinked to original sources

PubMed2006

Games network and application to PAs system.

In this article, we present a game theory based framework, named games network, for modeling biological interactions. After introducing the theory, we more precisely describe the methodology to model biological interactions. Then we apply it to the plasminogen activator system (PAs) which is a signal transduction pathway involved in cancer cell migration. The games network theory extends game theory by including the locality of interactions. Each game in a games network represents local interactions between biological agents. The PAs system is implicated in cytoskeleton modifications via regulation of actin and microtubules, which in turn favors cell migration. The games network model has enabled us a better understanding of the regulation involved in the PAs system.

Cell Movement↗

PubMed2003

Expression of the acetylcholine release mechanism in various cells and reconstruction of the release mechanism in non-releasing cells.

After loading cells in culture with acetylcholine (ACh), it was possible to identify cells that express a calcium-dependent release mechanism and cells that do not release. Mediatophore transfection restored the release capability of non-releasing cells. The transfection of choline acetyltransferase and the vesicular ACh transporter (VAChT) in cells that have already mediatophore in their membrane enables to study the effect of VAChT on the release kinetics. We also studied the properties of the mediatophore "pore" as a function of the concentration of ACh and also its temporal properties. A reconstruction of the release mechanism in cells particularly graftable cells, appears now possibly for ACh and probably for other transmitters.

Acetylcholine↗

PubMed2001

Functional evaluation in distal femoral endoprosthetic replacement for bone sarcoma.

A multicenter study of successfully treated patients (mean age, 36.7 years) with a minimum 1-year followup (average, 35.4 months) after distal femoral endoprosthetic replacement for bone sarcoma was done using the 1987 and 1993 versions of the Musculoskeletal Tumor Society, the Short Form-36, and the Toronto Extremity Salvage Score functional evaluation criteria. Fifty-six patients (28 women and 28 men) fulfilled the criteria. Thirty-one Kotz prostheses (fixed hinge, uncemented) and 25 Modular Replacement System Prostheses (rotating hinge, cemented) were used. Thirty-five patients walked without aids, 19 used a cane, and two used crutches or a walker. The Musculoskeletal Tumor Society 1987 mean score was 28.1. The Musculoskeletal Tumor Society 1993 mean score was 80.4. The Toronto Extremity Salvage Score mean was 81.6. The Short Form-36 Physical Component Score had a mean of 43.2 and Mental Component Score mean of 54.2. The two groups of implants were comparable, except for the length of bone resection. Multivariate regression analysis revealed that patient age, existence of a pathologic fracture, and type of prosthesis all significantly accounted for differences in functional outcome as measured by the Musculoskeletal Tumor Society 1993, the Toronto Extremity Salvage Score, and the Short Form-36 Physical Component Score scales. Although both implants provided satisfactory function, the Musculoskeletal Tumor Society 1993 and the Toronto Extremity Salvage Score results were significantly better with the Modular Replacement System prosthesis. The effect of possible differences among surgeons or institutions was not addressed.

Adult↗

PubMed2000

Effect of brefeldin A on acetylcholine release from glioma C6BU-1 cells.

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.

Acetylcholine↗

PubMed1999

Evoked acetylcholine release by immortalized brain endothelial cells genetically modified to express choline acetyltransferase and/or the vesicular acetylcholine transporter.

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.

Acetylcholine↗

PubMed1999

[Treatment of diaphyseal femoral fractures in children: a clinical study].

UNLABELLED: Many therapeutic modalities have been reported for the management of femoral shaft fractures in children and young adolescents but there is no consensus on the preferable method. PURPOSE: To compare the malunion rate of femoral shaft fractures in children treated either by traction and spica cast or traction and functional brace. MATERIAL AND METHODS: Between 1982 and 1984 a prospective study was carried out in a tertiary pediatric university hospital on 43 patients (24 boys, 19 girls) with a closed femoral shaft fracture. The patient's age ranged from 5 to 13 years old. Open, pathologic, subtrochanteric and physeal fractures were excluded. Fifteen (15) patients were treated by a functional brace and 28 were treated by a spica cast. Clinical and radiological assessments of all patients were performed 5 years or more after the fracture by an independent observer. A malunion occurred if one of these criteria were met: an angulation > or = 10 degrees in the coronal plane, an angulation > or = 15 degrees in the sagittal plane, a malrotation > or = 15 degrees by opposition to the other leg, and a discrepancy > or = 10 mm between femur's length. RESULTS: A malunion was found in 17 patients, 6 in the functional brace and 11 in the spica cast group (p > 0.05). The leg length discrepancy was the most common type of malunion. The length of stay was not significantly different between both treatment groups. The functional brace was worn longer than the spica cast. CONCLUSION: There was no statistical difference between the malunion rate of children treated by traction-spica cast and traction-functional brace. The functional brace appears to be a good alternative for the treatment for femoral shaft fracture in children allowing an earlier ambulation than spica cast.

Adolescent↗

PubMed1997

Manifestations and treatment of xerostomia and associated oral effects secondary to head and neck radiation therapy.

Xerostomia is one of the most common side effects of head and neck radiation therapy. Other oral effects are mucositis and radiation caries. Because xerostomia resulting from radiation therapy may be of a more permanent nature than xerostomia resulting from other causes, treatment is typically more extensive. Numerous regimens treat symptoms of xerostomia and associated caries and mucositis. Among them is the daily application of a fluoride gel, recommended to prevent or minimize dental caries. For patients with severe, chronic xerostomia who have some residual salivary tissue, the use of a sialagogue can promote an increased flow of saliva and treat the symptoms.

Cariostatic Agents↗

PubMed1989

Locus of control and anxiety in children from intact and maritally disrupted families.

This study investigated the associations of Locus of Control (Children Nowicki-Strickland Internal-External Control Scale) with state and trait anxiety (State-Trait Anxiety Inventory for Children) in 302 children aged 9 to 12 yr. No significant differences were found between the groups. No significant correlations were found between the anxiety measures and externality for the 31 children from maritally disrupted families, but significant positive Pearson correlations were found for the 271 children of intact families. The results are discussed in terms of the possibility of under-reporting of marital disruption by children.

Anxiety↗

PubMedDate not supplied

Ca2+ oscillations induced by fibroblast growth factor 2 in Xenopus oocytes expressing fibroblast growth factor receptors.

Double electrode voltage clamp technique was used to follow precisely the calcium signalling pathway activated by FGF receptors from a normal and a carcinogenous cell environment. Functional FGF receptors were expressed in Xenopus oocytes following either the injection of PFR1 cRNA from Pleurodeles, an homologue of the human FGFR1 mRNA, or breast cancer MCF7 cells total mRNA. Cytosolic calcium oscillations were monitored through the endogenous Ca(2+)-dependent Cl- channel activity from both RNA injected systems, under FGF2 treatment. The Ca(2+)-dependent Cl- channel was demonstrated using the Cl- channel blocker SITS (250 microM) and by the determination of the reversal potential of the Cl- ions close to -20 mV. The FGF2-evoked Ca(2+)-dependent Cl- current was abolished by external application of genistein (10 microM, tyrosine kinase inhibitor), neomycin (10 mM, phosphatidylinositol turnover inhibitor), caffeine (10 mM, inhibitor of Ins(1,4,5)P3-mediated release of intracellular calcium), and injection of BAPTA (50 microM, calcium chelator) or heparin (2 micrograms/ml, inhibitor of the binding of Ins(1,4,5)P3). The recorded current was independent of extracellular Ca2+ but involved tyrosine kinase phosphorylation and intracellular Ins(1,4,5)P3 sensitive stores. External application of heparin enhanced the oscillatory Ca2+ rise, suggesting a role for the heparan sulfates in the regulatory mechanism of the FGF receptors. The similarities in the Ca(2+)-dependent Cl- current obtained in PFR1 and total MCF7 FGF receptors expressing oocytes are discussed.

Animals↗

PubMedDate not supplied

Postsurgical management with maxillary obturators after maxillectomy.

A partial or complete maxillectomy may be required for the treatment of oral carcinoma, which may cause functional, esthetic, and hygienic deficiencies. The placement of a surgical obturator at the time of surgery can minimize these deficiencies and provide immediate facial rehabilitation, which can have important physical and psychological effects for the patient. Various types of obturators and the techniques used for the fabrication of different types of obturator prostheses are reviewed.

Dental Prosthesis Design↗