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Biomedical subjects

M Merle

Publications and source records attributed to M Merle.

At least 55 records · Page 3Linked to original sources
PubMed1993

Metabolic flux determination in C6 glioma cells using carbon-13 distribution upon [1-13C]glucose incubation.

A mathematical model of mammalian cell intermediary metabolism is presented. It describes the distribution of the carbon-13 isotope (13C) at the different carbon positions of metabolites in cells fed with 13C-enriched substrates. The model allows the determination of fluxes through different metabolic pathways from 13C- and 1H-NMR spectroscopy and mass spectrometry data. The considered metabolic network includes glycolysis, gluconeogenesis, the citric acid cycle and a number of reactions corresponding to protein or fatty acid metabolism. The model was used for calculating metabolic fluxes in a rat tumor cell line, the C6 glioma, incubated with [1-13C]glucose. After evolution to metabolic and isotopic steady states, the intracellular metabolites were extracted with perchloric acid. The specific enrichments of glutamate, aspartate and alanine carbons were determined from 13C-, 1H-NMR spectroscopy, or mass spectrometry data. Taking into account the rate of glucose consumption and of lactate formation, determined from the evolution of glucose and lactate contents in the cell medium, and knowing the activity of the hexose monophosphate shunt, it was possible to estimate the absolute values of all the considered fluxes. From the analysis the following results were obtained. (a) Glucose accounts for about 78% of the pyruvate and 57% of the CoASAc. (b) A metabolic channelling occurs at the citric acid cycle level; it favours the conversion of carbons 2, 3, 4, and 5 of 2-oxoglutarate into carbons 1, 2, 3, and 4 of oxaloacetate, respectively. The percentage of channelled metabolites amounts to 39%. (c) The pyruvate carboxylase activity and the efflux from the citric acid cycle are estimated to be very low, suggesting a lack of glutamine production in C6 cells. The results emphasize different metabolic characteristics of C6 cells when compared to astrocytes, their normal counterpart.

Alanine↗
PubMed1993

Glutathione, but not glutamine, is detected in 13C-NMR spectra of perchloric acid extracts from C6 glioma cells.

Glutamine, which is expected to be produced by C6 glioma cells, is not detected in both amino-acid analyses and 13C-NMR spectra of perchloric acid extracts of cells incubated for 4 h with [1-13C]glucose in the absence of extracellular glutamine. However, the resonances of a glutamate-linked product are observed in these spectra. The analysis of the pH dependence of chemical shifts from various glutamate-derived compounds shows that the observed resonances came from glutathione. Glutamine and glutathione signals are in close proximity on the frequency scale, leading to possible misinterpretation of the spectra.

Brain Neoplasms↗
PubMed1993

Percentage of nerve injuries in which primary repair can be achieved by end-to-end approximation: review of 2,181 nerve lesions.

Primary nerve repair yields better results than secondary reconstruction but is not always possible. We reviewed a series of 2,181 fresh nerve injuries of the upper limb. One nerve only was injured in 41% of the patients; two or more in 59%. One thousand four hundred eighty-two injuries (68%) were located in the digits. The injured limb segment was lost or beyond repair in 387 cases (18% of all cases). In the 1,794 remaining injuries, primary treatment was accomplished by end-to-end suture 1,568 times (87%) and by graft 33 times (> 2%) and was impossible in 193 cases (11%).

Anastomosis, Surgical↗
PubMed1993

N-acetyl-L-aspartate and acetate 1H NMR signal overlapping under mild acidic pH conditions.

The pH dependence of methyl proton chemical shifts of acetate, acetoacetate, N-acetyl-L-aspartate (NAA), and N-acetyl-L-aspartyl-L-glutamate (NAAG) were studied from pH 3 to pH 9. Only slight shifts of acetoacetate, NAA, and NAAG methyl signals were observed, whereas the acetate signal was largely shifted as a result of the titration of its acidic function. At pH 4.7, acetate and NAA methyl signals overlapped, whereas at more acidic pH, the acetate signal appeared downfield when compared to that of NAA. Results are discussed in terms of spectra misinterpretation risks linked to uncontrolled sample pH, on the one hand, and in terms of pH control and contamination by exogenous acetate during perchloric acid cell extract preparation, on the other.

Acetates↗
PubMed1993

Pronator quadratus free muscle flap for treatment of palmar defects.

Cutaneous flaps are not entirely satisfactory when used for soft tissue defects of the palm, because the skin cover is too mobile. Use of muscle flaps can therefore be advocated for this recipient site. A case is reported where the pronator quadratus muscle has been used as a free muscle flap for coverage of a small defect of the palm.

Adult↗
PubMed1993

Arthroscopic diagnosis of scapho-lunate instability in the absence of X-ray abnormalities.

26 patients with at least one clinical symptom that could indicate a tear of the scapho-lunate interosseous ligament but normal static and dynamic radiographs were examined by arthroscopy. We found that a diagnosis of scapho-lunate instability could be established by dynamic manoeuvres during radio-carpal and mid-carpal arthroscopy. Five patients were found to have true scapholunate instability. Six tears of the interosseous ligament without instability were also detected but it was doubtful if the tear was the origin of the painful symptomatology. This experience suggests that dynamic manoeuvres during arthroscopy are superior to other methods in diagnosing scapholunate instabilities at the pre-radiographic stage.

Adolescent↗
PubMed1993

[Dynamic arthroscopic tests for the diagnosis of scaphoid-lunar instabilities].

Diagnosis of scapholunate instability can be established even when static and dynamic X-Rays are normal. Dynamic manoeuvres during wrist arthroscopy are superior to other testing methods in diagnosing scapholunate instability at these early stages. Evaluation of ligament remnants during arthroscopy is also helpful when selecting the appropriate treatment option.

Arthroscopy↗
PubMed1993

[Arthrodesis of 4 bones of the wrist. Study of 12 follow-up cases].

From November 1988 to December 1990, 15 four-bone fusions (capitalum-lunatum-triquetrum-hamatum) were performed in our department. 3 cases were lost at follow-up, so we here describe 12 cases reviewed for a clinical and radiologic evaluation. Etiologies were as follows: advanced scapholunate dissociation: 5 cases; advanced pseudarthrosis of the scaphoid: 6 cases; ulnar midcarpal instability: 1 case. Follow-up averaged 18.8 months with a range of 6 to 29 months. Pain was significantly lessened: 9 patients had either no pain, pain influenced only by weather, or pain after sustained effort. Results for strength were average. Joint motion was severely restricted, with individual variations among patients. Remaining joint motion was of little use, and some activities of daily living were thus hampered. Pre and postoperative radiologic analysis of the carpus showed that repositioning the proximal row into the distal row of bones was not necessary. In order to obtain a good result, it suffices to stabilize the existing carpal collapse without attempting to restore carpal height. Study of this short series showed the efficacy of this arthrodesis as regards to pain although it significantly decreased the range of motion.

Adult↗
PubMed1993

[Correction of posttraumatic disorders of the distal radio-ulnar joint with the Sauvé-Kapandji surgical procedure].

The Sauve-Kapandji procedure was performed on 21 patients with posttraumatic lesions between May of 1985 and May of 1991; average clinical and radiological follow-up was 3.4 years. Causal mechanisms were as follows: 12 cases were sequelae of fractures of the distal extremity of the radius; 5 cases were sequelae of fractures of the diaphyses of the two forearm bones and/or of the head of the radius; 2 cases of instability of the distal radio-ulnar joint; 2 cases of posttraumatic isolated arthritis of the distal radio-ulnar joint. Subjective evaluation by the patients of the results of surgery was as follows: 8 excellent, 6 good, 2 satisfactory and 5 poor. The most consistent improvement was a gain of mobility in pronation and supination which averaged 87 per cent of that of the healthy contralateral side. Nine patients were free of pain, 6 experienced some pain only during effort, and 6 still suffered constant pain. Grip strength was the factor that changed the most: it averaged 55 per cent of that of the healthy contralateral side. Indications for the Sauve-Kapandji procedure and its results in posttraumatic lesions are discussed. This procedure is compared to other techniques used to correct posttraumatic disorders of the distal radio-ulnar joint.

Adolescent↗
PubMed1993

[Arthrolysis of the wrist, indications and technique].

The authors describe a technique of arthrolysis which can be used on the palmar aspect of the wrist, on the dorsal aspect, or on both capsular and ligamentous complexes. The procedure must not be performed before inflammation and retraction phenomena of capsular and ligamentous complex have completely ceased. The surgical procedure must be followed rigorously but is not especially difficult. Criteria for patient selection are emphasized because proper indication is crucial to ensure satisfactory results.

Adult↗
PubMed1992

Beta-adrenergic stimulation of C6 glioma cells: effects of cAMP overproduction on cellular metabolites. A multinuclear NMR study.

We used 31P-NMR spectroscopy to investigate the response of living C6 glioma cells to stimulation by a beta-adrenergic agonist, isoproterenol. In the presence of 3-isobutyl-1-methylxanthine, stimulation induced an accumulation of cAMP, making possible the NMR detection of the second messenger in living cells grown on microcarrier beads and perfused in the NMR tube. The cAMP signal rose to a maximum level within 20-25 min of stimulation; thereafter it decreased to the detection threshold within 60 min. At the same time, 40% increases of phosphomonoester and diphosphodiester signals were observed, whereas no significant change in phosphocreatine and nucleotide signals was detected. The kinetics of changes of the cellular content in phosphorylated metabolites were analyzed after recording 31P-NMR spectra of cell perchloric acid extracts as a function of time of stimulation. cAMP accumulation in stimulated cells was evidenced by a near linear increase of its NMR signal as a function of incubation time (from 0 to 60 min). Concomitantly with the production of cAMP, the data showed 30% decreases of phosphocreatine and ATP levels within 60 min of stimulation, and an unexpected redistribution of pyrimidine and purine nucleoside triphosphates. At the same time, levels of phosphomonoesters (phosphorylcholine and phosphorylethanolamine) and phosphodiesters (glycerophosphorylcholine and glycerophosphorylethanolamine) rose (50% increase). 13C-NMR spectra of cell perchloric acid extracts prepared after isoproterenol stimulation of cells incubated in the presence of [1-13C]glucose indicated a higher glucose content in stimulated cells, whereas the resonance of ribose C1 was diminished. Moreover, the resonances of C1 of ethanolamine and choline (and their derivatives) were increased in spectra of stimulated cells, whereas that of C3 of serine was decreased. In addition, the 13C-NMR data indicated that neither the pattern of glutamate carbon enrichment nor the glutamate/glutamine ratio was modified in stimulated cells. On the other hand, the heteronuclear coupling pattern of the lactate (methyl group) resonance in 1H-NMR spectra of cell incubation media indicated that no change occurred in the carbon flux through the pentose-phosphate shunt under stimulation. The results of this multinuclear NMR approach are discussed in terms of metabolic responses of C6 cells to beta-adrenergic stimulation and cAMP overproduction.

Adenosine Triphosphate↗
PubMed1992

Scapho-trapezio-trapezoid arthrodesis in the treatment of Kienböck's disease. A study of 16 cases.

Sixteen scapho-trapezio-trapezoid arthrodeses were performed for Kienböck's disease. In ten cases, a prosthetic replacement of the lunate was inserted at the same time. Clinical results were good with regard to pain and fair with regard to grip strength which was improved by an average of 32%. In contrast, the arc of flexion-extension was 38% less than on the unoperated side. Long-term radiographic assessment showed the efficacy of the procedure in maintaining carpal height. Biomechanical observations and a review of poor results showed the limits of the method and the importance of correct positioning of the scaphoid. We concluded that triscaphe arthrodesis was a useful procedure for the treatment of Kienböck's disease in Decoulx's stage 3.

Adult↗
PubMed1992

The blood supply of digital nerves: a microanatomical study of superficial and deep palmar venous networks.

In this work on vascularization of digital nerves, we have studied the anatomy of the deep network of venae comitantes of digital arteries, and the system of superficial palmar venules. 22 specimens of nerve and artery were dissected as one unit and were infused with Microfil prior to study under the microscope. The deep venous network, a satellite of the digital artery, can be classified into four types. A true network of deep venae comitantes exists in three of these four types, drained by deep veins arising from the transverse anastomotic arches between the palmar digital pedicles. Vascularization of the digital nerve is supplied by numerous anastomotic vessels connecting epineurial vessels, digital artery and the periarterial network (venae comitantes and vasa vasorum). This anatomical configuration lends itself to vascularized nerve grafting; for example, it is possible to use a nerve/artery graft taken as a unit from an amputated finger unsuitable for replantation. Two types of valves in this superficial venous network have been identified and their function is discussed.

Adult↗
PubMed1992

[Lipofibroma of the median nerve. Apropos of a case].

Lipofibroma is a rare, benign nerve tumour corresponding to diffuse fibroadipose infiltration of the nerve, dissociating the fasciculi without invading them. The authors report a case of lipofibroma of the median nerve in a 32 year old man presenting with a soft swelling of the palmar surface of the thumb. Treatment consisted of intraneurodissection of the tumour arising exclusively from the medial collateral nerve of the thumb. With a follow-up of two years, there has been no recurrence of the tumour, but the patient has persistent decreased sensation of the ulnar half of the thumb pulp. The features of the lipofibroma and the therapeutic options are discussed in the light of the data reported in the literature.

Adult↗