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Biomedical subjects

J Michon

Publications and source records attributed to J Michon.

At least 145 records · Page 8Linked to original sources
PubMed1986

Highly polymorphic products of both HLA-DR and HLA-DQ genes contribute to the polymorphism of the HLA-DRw13 haplotype.

We studied the polymorphisms of HLA-DR and HLA-DQ products from HLA-DRw13 haplotypes by analyzing the restriction of influenza A-specific cloned T cells from an HLA-DRw13,DQw1,Dw19 homozygous individual. The results show that some functional epitopes, which can be borne by either HLA-DR or HLA-DQ molecules, are strictly correlated with the HLA-Dw19 subtype of HLA-DRw13. This clearly indicates that both HLA-DR and HLA-DQ products contribute to the HLA-Dw19 subdivision of HLA-DRw13. At least two different restricting epitopes are borne by DR products: one is correlated with the HLA-DRw13 serologically defined specificity, which includes Dw19 and Dw18 haplotypes; the other is correlated with the only HLA-Dw19 subtype of HLA-DRw13. Restricting epitopes borne by DQ molecules have been found on Dw19 cells only. DQ-restricted clones were unable to react with DQw1 APC of any other haplotypes tested, including DR1, DR2-long, DR2-short, and DRw14, demonstrating a high degree of functional polymorphism among the serologically defined DQw1 specificities.

Antigen-Presenting Cells↗
PubMed1986

Despite lack of monospecific anti-DRw13 sera, a corresponding class II determinant can be defined by a DRw13 restricted anti-influenza virus T cell clone.

The study of a T3+ T4+ T8- human T cell clone COTC2 with both specific proliferative response and cytolytic activity for influenza A virus infected cells reveals that: the restricting element of this clone is strongly associated with DRw13 molecule(s) as seen by the study of a large panel of antigen presenting cells (APC) and by the observation that monoclonal antibodies (MoAb) specific for DR molecules inhibit its proliferative activity while anti-DQ MoAb do not. These results indicate that there exists a DRw13 associated determinant that can be defined at the functional level by COTC2 recognition despite the absence of monospecific anti-DRw13 serum. In contrast to the results found by other groups, the restriction of this DRw13 restricted clone follows the DRw13 serological definition irrespective of the DW type of the APC. These results indicate that the polymorphism of HLA class II molecules can be further defined at the functional level by monoclonal populations of T cells in conjunction with molecular definition.

Antibodies, Monoclonal↗
PubMed1985

Free vascularized nerve grafts: an experimental study in the rabbit.

An experimental animal model of a vascularized graft is presented as an alternative to recover faster function. The technique is described and the model compared to a conventional graft in the sciatic nerve of a rabbit. Results are evaluated with histological studies and quantified using a computer to measure the thickness of the myelin sheath as a correspondence factor of regeneration. Results showed a more favorable regeneration when a vascularized graft was used.

Animals↗
PubMed1985

Fine specificity analysis of human influenza-specific cloned cell lines.

Influenza-specific human-T-cell clones, proliferating in the presence of virus-infected cells with restriction by class II molecules and displaying class II-restricted CTL activity or specific helper activity in antibody synthesis, have been analyzed for antigenic specificities. All of them were obtained by in vitro stimulation against influenza A/Texas virus. In all cases the virus specificity appeared identical in cytolytic and proliferative responses. Three of the clones were broadly cross-reactive, recognizing all or almost all type A influenza strains. The three remaining clones were subtype specific when tested with human strains and recognized the surface glycoproteins of influenza virus. One of these lines reacted with an epitope of the neuraminidase N2 while the other two recognized the hemagglutinin H3. By using a large panel of mammalian and avian influenza strains, it can be demonstrated that hemagglutinin-specific human T cells can recognize a cross-reacting determinant shared by H3 and H4 subtypes of hemagglutinin which has never been detected with antibodies.

Animals↗
PubMed1985

Thumb reconstruction pollicisation or toe-to-hand transfers. A comparative study of functional results.

A statistical study of thumb reconstruction after traumatic amputation, based on the records of 33 pollicisations and 21 microsurgical toe-to-hand transfers was made. A precise method of evaluation of results is presented. The types of lesions are divided into 4 groups; 1: amputation of the thumb without injuries of the other fingers; 2: amputation of the thumb associated with amputations or mutilation of other fingers; 3: metacarpal hand; 4: amputation of the thumb distal to the metacarpophalangeal joint. The aim of this study was to determine the respective indications of the two methods. It may be concluded that: in group 1, the results of pollicisation and of toe-to-hand transfers are similar. The former is superior as far as the discriminative sensory and fine motor results are concerned, while toe transfer reestablishes better strength. In group 2, the more the other fingers are mutilated, the more toe transfers should be preferred to pollicisation which weakens the performance of the long fingers, especially when they are injured. In group 3 (metacarpal hand), the transfer of one or more toes is a revolution. It is the only technique capable of returning function and, if technique is correct, a cosmetically satisfactory aspect as well. In distal amputations of the thumb (group 4), the only indications for pollicisation are cases of a proximally injured finger with a healthy distal segment, transferable on healthy pedicles, which is relatively rare. Partial toe-to-hand transfers, is a new solution to this challenge.

Amputation, Traumatic↗
PubMed1984

Single stage thumb reconstruction by a composite forearm island flap.

Single stage thumb reconstruction is possible with a new composite skin bone flap from the forearm. The primary vascularisation of skin and bone avoids the disadvantages of the conventional multi-staged procedures such as neurovascular insufficiency, infection and bone absorption. It does not require a surgical team with microsurgical expertise. The best indication is the reconstruction in the subtotal thumb amputation.

Adult↗
PubMed1984

Functional comparison between pollicization and toe-to-hand transfer for thumb reconstruction.

The functional results of two methods of thumb reconstruction, pollicization, and toe transplantation were evaluated in four groups of patients: Group I, those missing the thumb but with four other normal digits; Group II, those missing the thumb with partially mutilated or amputated other digits; Group III, those with a metacarpal hand; and Group IV, those with a distal thumb amputation. In each group, results were compared in six categories: mobility, strength, sensibility, cosmetic appearance, pinch accuracy, and grasping power. In Group I, pollicization provided superior sensibility and mobility, but grasping power was best achieved by transfer of the big toe. Second toe transfer and pollicization both resulted in some weakness, compared with the normal hand. Pinch accuracy, related to the quality of sensibility, was better achieved by pollicization than by any free transfer. In Group II, although pollicization of a mutilated digit is more controversial, a very good functional level was reached in some cases, directly related to the amount of preoperative sensibility and the mobility of the proximal interphalangeal joint in the transferred digit. Reduction of strength and prehension depended on the number and quality of the remaining nontransferred digits. Toe transfer yielded better results in all six categories, as the severity of digit mutilation increased. In Group III, pollicization of the second metacarpal achieved a very rudimentary pinch, with toe transfer allowing for much greater prehension possibilities. In Group IV, distal thumb amputations were treated with distal digital pollicization as well as with partial toe transplantation. Both methods did well; however, indications for pollicization were extremely limited. Comparing results of big and second toe transfer for thumb reconstruction, big toe transfer achieved superior results, in both functional and cosmetic aspects.

Amputation, Traumatic↗
PubMed1984

The repair of peripheral nerve injuries in emergency.

Peripheral nerve injuries must be considered as serious surgical emergencies for they are often associated with vascular lesions. Primary repair of clean-cut injuries of peripheral nerves by microsurgical techniques yields better results than the best of secondary repairs.

Electromyography↗