Switching reciprocity on and off in a magneto-optical x-ray scattering experiment using nuclear resonance of α-(57)Fe foils.

Reciprocity is when the scattering amplitude of wave propagation satisfies a symmetry property, connecting a scattering process with an appropriate reversed one. We report on an experiment using nuclear resonance scattering of synchrotron radiation, which demonstrates that magneto-optical materials do not necessarily violate reciprocity. The setting enables us to switch easily between reciprocity and its violation. In the latter case, the exhibited reciprocity violation is orders of magnitude larger than achieved by previous wave scattering experiments.

[Evaluation of an immunoradiometric assay for succinylated ACTH]. / Evaluationdudosageimmunoradiométrique de l'ACTH succinylée.

A new immunoradiometric assay for succinylated ACTH using 3 monoclonal antibodies has been developed by Immunotech (I-IRMA). It was compared to a commercial immunoradiometric assay of ACTH (Nichols Institute, N-IRMA). The functional sensitivity of I-IRMA assay was estimated at 1.5 ng/L. The comparison of both methods on plasma samples withdrawn at 8 h from 47 normal subjects showed a good correlation coefficient (r = 0.83; P < 0.001). The 24-hours secretion profiles obtained by both methods were similar in 14 normal subjects. Nevertheless, the I-IRMA mean values were about 30% lower than the corresponding N-IRMA values. This difference increased to 50% when the ACTH concentrations were low, as it the case at 24 h or during the dexamethasone suppression test. During insulin hypoglycemia stimulation test, the two procedures gave similar values. Both methods applied to a pathologic population gave similar result to those obtained on normals. In 10 patients bearing corticotroph adenomas, the profiles of ACTH secretions during 24 h were similar using both methods. The I-IRMA values were lower about 30% than N-IRMA values during the base state or after the 8 mg-dexamethasone suppression test. This difference was also observed in 6 patients with corticotroph insufficiency. In conclusion, the comparison of N-IRMA and I-IRMA methods showed the validity of the new succinylated-ACTH assay which is more efficient in the lower range of ACTH concentration. This significant decrease in the sensitivity threshold may be useful in the establishment of the cure criteria in Cushing disease.

Immunoradiometric assay of succinylated corticotropin: an improved method for quantification of ACTH.

In this paper we describe the development and the evaluation of a new type of immunoassay for human corticotropin (ACTH). We succeeded, by using an original approach based upon immunization with ACTH derivatized with succinic anhydride, in raising monoclonal antibodies against this poorly immunogenic peptide. Three of the antibodies were selected to develop an immunoassay for ACTH. The assay requires the prior succinylation of the plasma samples for optimal sensitivity and specificity. This acylation treatment is fast, reproducible, and, in addition, improves the stability of the ACTH molecule in plasma, thus facilitating sample handling. The assay is performed in only 3 h with a detection limit of 0.7 ng/L. Analytical evaluation showed excellent specificity, reproducibility, and reliability. A comparison with two commonly used but time-consuming ACTH IRMAs was carried out by assaying several plasma samples in parallel and gave in both cases very good correlation.

A novel method for the production of antibodies against ACTH: their characterization and use in epitope mapping.

Our earlier attempts at immunization with human adrenocorticotropin hormone (ACTH) were unsuccessful and we therefore developed a new strategy including the chemical modification of the hormone by succinic anhydride in order to increase its immunogenicity. This process allowed us to obtain antisera with titers of up to 1/1000 and yielded 39 anti-succinylated ACTH (sACTH)-secreting hybridomas. Subsequently, the epitopes of sACTH were mapped by testing monoclonal antibodies two by two for simultaneous binding to sACTH and for their capacity to recognize its succinylated fragments 1-13, 1-17 and 1-24. The results, obtained with the use of radioactive tracers, were confirmed by and complemented with experiments conducted with biosensor technology. Seven groups of antibodies were defined on the basis of their pattern of reactivity and it was shown that four monoclonal antibodies could bind simultaneously to sACTH. Their dissociation constants (Kd) for sACTH were calculated and ranged from 10(-8) M to 10(-11) M. In order to obtain a fast and sensitive immunoassay for the hormone, we developed a protocol for the chemical modification of ACTH in serum and the most efficient monoclonal antibodies were selected on the basis of the epitope map and of their dissociation constants.

[Late post-tracheostomy airway complications in patients with central nervous system injuries]. / Központi idegrendszeri sérültek késöi posttracheostomiás légúti szövödményei.

At decannulation or often weeks later some of the patients undergone long-term mechanical ventilation through tracheostoma reveal symptoms of airway stenosis. Posttracheostomy airway complications detected during the rehabilitation of 34 patients with central nervous system injury are presented. Endoscopic examinations (total 130) were performed with Olympus BF B3 and OES 20-type fiberscopes and Friedel-type rigid bronchoscopes under local or general anaesthesia. Stridor (20 cases) and possible decannulation (10 cases) were the main indications of the first endoscopic examinations. Stridor was caused by tracheal (12 cases) and laryngeal (8 cases) stenosis. With six patients decannulation was possible after the first endoscopy. Removal of granulomas and sutures was successful in 8 cases. Rigid bronchoscopic dilatations were temporarily successful in 7 cases, but in five of them it had to be repeated on emergency. Further therapeutic interventions were: recannulation (3 cases), retracheostomy (4 cases), implantation of silicon T-endoprothesis (5 cases), tracheal resection (4 cases). Three patients are discussed in details. Eliminating airway complications largely contributed to rehabilitation of the nervous and musculoskeletal system, improved the quality of life, and in acute cases it was a life-saving measure. In order to prevent the development of late airway complications or detect them in time, it is recommended to have an endoscopic protocol following every tracheostomy: 1. at the time of decannulation 2. at closing the trachea and 3. 2-3 months after decannulation.

[Surgery of infected hand injuries in Bács-Kiskun County]. / A septicus kézsebészet fejlödése Bács-Kiskun megyében.

The therapy of the diseases of the infected hand belongs to the most difficult tasks of the hand surgery. In the county Bács-Kiskun we have reached important results during the last two decades, described in this paper, together with the Hand Surgery Work Groups of the Accident Departments of Kecskemét (County Hospital), Baja and Kiskunhalas.