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Biomedical subjects

M Merle

Publications and source records attributed to M Merle.

At least 91 records · Page 5Linked to original sources
PubMed1991

Human nerve xenografting in nude mouse: experimental study of graft revascularization.

In the nude mouse, the congenital absence of T lymphocytes makes it possible to implant human nerve grafts without rejection or iatrogenic modifications (by immunosuppression) of human and murine tissues. Medial antebrachial cutaneous nerves were harvested from human cadavers 1-18 hours after death. These nerve grafts were implanted using different techniques in nude mice. All the grafts were macroscopically and microscopically revascularized 3 days after implantation. The modifications in time of this vascularization could be studied with precision through the use of repeated biopsies. The absence of human blood group antigens on the neovessel endothelium suggested a murine origin for angiogenesis. In situ DNA hybridizations with human and mouse DNA confirmed this origin. The topography of the revascularization (maximal in the perineurium and endoneurium) and the almost complete absence of human cells other than Schwann cells in the grafts at the peak of angiogenesis (26 days after grafting) suggested that Schwann cells had a determining role in graft vascularization. The irradiation of the nerve grafts with a dose of 30 grays before implantation did not modify significantly their histologic appearance compared to the control group, whereas an irradiation of 60 grays led to massive lesions. The neurotization of murine axons led to chimerical structures of normal histologic appearance, with vascularization similar to that observed in nonneurotized nerves. Through chimerism (human Schwann cells, murine vessels and axons) this model makes it possible to dissociate the respective role of the host and of the nerve graft in angiogenesis and suggests the existence of growth factors produced by the human Schwann cells.

Adult↗
PubMed1991

Dorsal metacarpal reverse flaps. Anatomical basis and clinical application.

The presence of distal intermetacarpal anastomoses between dorsal and palmar vascular networks makes it possible to raise distally-based cutaneous island flaps oriented along the axis of the dorsal metacarpal arteries. These flaps receive a reverse-flow vascularisation. Distal intermetacarpal anastomoses were found consistently in 35 hands from adult cadavers. The exact location of these anastomoses varied with the course of the dorsal metacarpal artery. Thus, island flaps can be raised consistently from the dorsal aspect of the hand and rotated around a distal intermetacarpal pivot. These flaps are suitable for covering the dorsal aspect of the proximal phalanx and the proximal interphalangeal joint.

Adolescent↗
PubMed1991

Vascularised nerve grafts.

Since Taylor (1976) successfully performed the first vascularised free nerve graft, experimental and clinical data have not provided conclusive support for the superiority of this method of repairing loss of nerve substance. Experimental work yields conflicting results. Histologic results are in favour of vascularised grafts but non-vascularised fascicular grafts placed in a healthy bed recover sufficient neovascularisation within a short period of time (four to six days). In the field of brachial plexus repair, vascularised grafts give consistent results. However, if thrombosis of the anastomoses occurs, the grafts fail completely. In our experience, vascularised nerve grafts used for repairing digital nerves and arteries, have a high rate of thrombosis. There are few potential donor sites. A nerve graft cannot be considered to be physiologically vascularised if it relies only on an artery or on an arterialised vein. Given the present state of immunosuppressant treatments, vascularised allografts are not yet appropriate. Therefore, vascularised nerve grafts have limited applications. In general it is preferable to repair the tissue bed so as to promote revascularisation of conventional nerve grafts.

Adult↗
PubMed1991

Applying "cell surgery" to nerve repair: a preliminary report on the first ten human cases.

We have applied a new technique of nerve repair, based on the principles of "cell surgery", to ten nerve lesions of the upper limb. Eight lesions were recent, five to 36 hours; they were divisions of the ulnar nerve (1), median nerve (2), sensory radial nerve (1), palmar and digital nerves (4). One lesion was 15 days old (median nerve). One eight-month-old loss of 4.5 cm. of the median nerve was grafted. In nine out of the ten cases, the short-term results were encouraging. Poor local conditions (fibrosis of the nerve bed) or poor general health (chronic alcoholism) had no adverse influence on the results. In the remaining case, the protocol was not followed in its entirety: it was not possible to crystallise properly the nerve, and trimming was done with scissors in the conventional way instead of smoothly trimming the solidified tips. The functional result in this case is a failure. These preliminary results seem to indicate that correctly applying the technique in its entirety may be more important than local conditions. We think that this technique can be applied to the majority of nerve lesions. The appropriate equipment is absolutely necessary in order to apply the method.

Adolescent↗
PubMed1991

Magnetic resonance spectroscopy and metabolism. Applications of proton and 13C NMR to the study of glutamate metabolism in cultured glial cells and human brain in vivo.

Nuclear magnetic resonance (NMR) spectroscopy was used to study the metabolism of cells from the central nervous system both in vitro on perchloric acid extracts obtained either from cultured tumoral cells (C6 rat glioma) or rat astrocytes in primary culture, and in vivo within the human brain. Analysis of carbon 13 NMR spectra of perchloric acid extracts prepared from cultured cells in the presence of NMR [1-13C] glucose as substrate allowed determination of the glutamate and glutamine enrichments in both normal and tumoral cells. Preliminary results indicated large changes in the metabolism of these amino acids (and also of aspartate and alanine) in the C6 cell as compared to its normal counterpart. Localized proton NMR spectra of the human brain in vivo were obtained at 1.5 T, in order to evaluate the content of various metabolites, including glutamate, in peritumoral edema from a selected volume of 2 x 2 x 2 cm3. N-acetyl aspartate, glutamate, phosphocreatine, creatine, choline and inositol derivative resonances were observed in 15 min spectra. N-acetyl-aspartate was found to be at a lower level in contrast to glutamate which was detected at a higher level in the injured area as compared to the contralateral unaffected side.

Animals↗
PubMed1991

Pedicled or free flap transfer of the gracilis muscle in rats.

The vascularization of the gracilis muscle of the rat is oriented mainly along the longitudinal axis of the muscle and arises from a muscular artery originating in the femoral artery. Transillumination study of the muscle after vascular injection with Microfil demonstrated this anatomic disposition. The gracilis muscle was used either as a pedicled transfer or as a free flap with anastomoses placed on the femoral pedicle. Average weight of the muscle before transfer was 429 mg. The cutaneous area of the muscular artery could be used to monitor the flap or to accomplish a composite myocutaneous transfer. This muscle flap is a versatile and reliable model for experimental study of muscle transfer in rats.

Animals↗
PubMed1991

[Arthrodesis of the wrist in manual workers. Apropos of 36 cases].

We present a review of 36 patients with final radiocarpal arthrodesis done between 1976 and 1987. The series was homogeneous: patients were about 40 years old and lesions were work-related. The most frequent reason for the arthrodesis was fracture of scaphoid bone, followed by Kienbock's disease complex trauma of carpus, severe carpal sprain, and articular fracture of the distal fourth of radial bone. Thirty-one arthrodeses were done by screwed-on iliac graft, 5 by nailing following Mannerfelt technique. The two main factors in functional results were pain and loss of strength. The latter averaged 41 per cent of that of the normal side, and only 8 wrists were completely free of pain. Indications for final radio-carpal arthrodesis are discussed, taking into account the poor functional results and their repercussions on social and professional life of the patient.

Accidents, Occupational↗
PubMed1991

[Partial toe transfers. Functional results: apropos of 26 cases].

We present our results from a series of 26 partial toe transfers (11 pulp transfers and 15 composite tissue transfers) performed in posttraumatic reconstruction of the thumb (22 cases) and fingers II to V (4 cases). There was one failure due to arterial thrombosis. The results for sensitivity were satisfactory after pulp transfer (Weber-average of 9 mm), less satisfactory after composite transfer. Recovery of mobility and strength usually were satisfactory. Problems with the donor foot were mainly slow healing and poor tolerance to cold; the latter was experienced by 1/3 of the patients although functional deficits were rare. Partial toe transfer is used at present for distal reconstruction of the thumb, and leaves the metacarpophalangeal joint intact. There are basically two techniques: "tailored" transfers from the big toe for amputations of the distal phalanx of the thumb, and wrap-around flap of Morrison for amputations proximal to the proximal phalanx.

Adolescent↗
PubMed1991

[Scapho-trapezo-trapezoidal arthrodesis or triscaphe arthrodeses. Study of 36 reviewed cases].

From May 1983 to September 1988, we performed 41 triscaphe arthrodeses, 36 of which underwent clinical and radiologic follow-up examination. The 36 preoperative diagnoses were classified as: Kienböck's disease (16 cases), chronic rotatory subluxation of the scaphoid (static scaphoid-lunate dissociation) (13 cases), degenerative arthritis of the scapho-trapezio-trapezoid joint (4 cases), traumatic lesion of the scapho-trapezio-trapezoid joint (2 cases), 1 case of midcarpal instability with a non-dissociative VISI pattern. Average length of follow-up was 28 months. Analysis of results showed on the whole good improvement on pain and average improvement of strength; range of motion varied greatly with etiology. For example, the range of motion on the fused side in Kienböck's disease averaged 38 per cent of that of the unoperated side, whereas in other conditions it averaged 60 per cent. Radiographic analysis confirmed the efficacy of triscaphe arthrodesis in preserving normal carpal height but revealed radial styloid impingement in 34 per cent of the cases. Use of this procedure should be limited to stage 3 Kienböck's disease and to scaphoid-lunate dissociation without arthritis. Peroperative radiographic study is indispensable to verify appropriate reduction of the scaphoid and to measure the radial-scaphoid angle. Partial radial styloidectomy should be included routinely in the procedure.

Adult↗
PubMed1990

[The lower radio-ulnar joint in malunion of the lower end of the radius: therapeutic implications].

Malunion of the lower extremity of the radius is frequently accompanied by a lesion of the inferior radio-ulnar joint marked by inversion of the inferior radio-ulnar index. Surgical treatment must always take this parameter into account and should attempt to correct it. The authors' preference in the treatment of malunion consists of Duparc osteotomy, in which the size of the graft is calculated in order to restore the inferior radio-ulnar index. If the correction is insufficient or in the case of moderate malunion, the authors propose the Kapandji-Sauvé operation which allows better preservation of the wrist stability.

Adult↗
PubMed1990

[Nerve graft of collateral branches of fingers. Report of a series of 16 reviewed cases].

Sixteen digital nerve grafts (14 patients) were reviewed with an average follow-up of 43 months. Average age was 27 years (7-53 yrs). Eleven grafts were performed on the thumb or the index finger. The nerve lesion was always proximal to the proximal interphalangeal joint, and associated with a tendinous lesion in one case out of two. One graft was done in emergency, 6 for failure of sutures and 7 for neglected wounds. Delay before grafting was on average of 4 months (0-16 months). The n. cutaneus antebrachii medialis was used in 11 patients. An hypoesthetic area of an average of 78 cm2 was noted, at the inferomedial part of the forearm, but only one patient complained with discomfort. At follow-up 3 patients, all under 20, had discriminative sensibility, 4 had protective sensibility and 5 only some sensibility to touch. Half of our patients complained with little discomfort, but 9 of 14 suffered with cold among which two suffered daily.

Adolescent↗
PubMed1990

Osteopathia striata with cranial sclerosis.

We report a case of osteopathia striata, which is an osseous dysplasia with linear striations of the metaphyses of long bones. Our case is very unusual as there are no associated abnormalities of the bones. Osteopathia striata should not be mistaken for osteopoikilosis. Osteopathia striata is not only a peculiar roentgenologic feature: when it is diagnosed other abnormalities should be looked for, especially cranial osteosclerosis, which may result in complications.

Adult↗
PubMed1990

[Extensive skin losses of the upper limb].

The development of microsurgical techniques and of pedicled local flaps has improved the prognosis of major injuries of the upper limb. Pedicled muscle-skin flaps from the latissimus dorsi muscle allow repairing losses of substance in the arm-pit and arm while restoring the function of the elbow. In the forearm, the same flap, transferred by microsurgery, ensures the rehabilitation of the wrist and hand. In the hand, the Chinese and posterior interosseous flaps allow covering the losses of substance on both the palmar and the dorsal aspects. Here, the free flaps are used only if the palmar vascular arches of these interosseous anastomoses are affected. Lastly, remote flaps are required only for the contraindications of microsurgery. Thus, using this array of donor sites, the emergent replacement of the most complex losses of sin substance can be performed, thus fostering the repair and protection of fony, neurovascular and tendon lesions.

Arm↗
PubMed1989

ADP and, indirectly, ATP are potent inhibitors of cAMP production in intact isoproterenol-stimulated C6 glioma cells.

When added to intact C6 glioma cells in the micromolar range of concentrations, ADP and ATP induce an inhibition of the isoproterenol-elicited cAMP responses. ATP is rapidly hydrolyzed by the ectonucleotidases present on these cells, with an apparent Km of 50 microM and a Vmax of 1.1 nmol/min/10(6) cells. cAMP responses are also inhibited by millimolar concentrations of either ATP in the presence of an ATP-regenerating system to prevent ADP accumulation or AMP-PCP. These observations show that, in C6 glioma cells, ADP is a more potent inhibitor of cAMP production than ATP, the latter acting indirectly, via its rapid hydrolysis to ADP. The additive inhibition of isoproterenol-elicited cAMP responses induced, on one hand, by the treatment of the cells with a phorbol ester and by addition of ADP to the cells, and, on the other hand, by the progressive disappearance of the effects of ADP and ATP when cells are treated with increasing concentrations of Pertussis toxin, demonstrate that ADP and ATP exert their action in C6 glioma cells via a P2 purinoceptor probably negatively coupled to adenylate cyclase and a G regulatory protein.

Adenosine Diphosphate↗