[Preoperative X-ray computed tomographic evaluation of major aplasia of the ear in children]. / Bilan tomodensitométrique pré-opératoire des aplasies majeures de l'oreille chez l'enfant.

PURPOSE: To describe computed tomography (CT) findings in congenital aural atresia (CAA) and to illustrate the impact of these findings in the preoperative evaluation. MATERIALS AND METHODS: Sixty-seven congenital aural atresia (bilateral: 10) in 57 children were studied using high resolution CT. Sections 1.5 mm thick were removed from the coronal and the axial plans without sedation (mean age: 9, 6 years). RESULTS AND DISCUSSION: A narrow bony external auditory canal (EAC) was present in 24% of the cases. In one of these cases, the EAC contained a cholesteatoma and was consequently a clear indication of surgery. An hyperpneumatized mastoïd (22%), a posterior position of the temporo mandibular joint (16%), and a bulging medial temporal fossa (12%) made the operation much more difficult. The tympanic cavity was small in 68% of the cases, normal in 28% and absent in 4% of the cases without any detectable ossicular chain. Ossicular chain anomalies were present in 91% of the cases. This consisted most frequently of a fusion of the malleus and the incus (76%) with or without fusion to the tympanic wall (33%). Lateral and anterior displacement of the descending portion of the facial nerve was present in 62%. Oval and round windows were normal in 86% of the cases. A soft tissue opacity (33%) in the tympanic cavity made it difficult to evaluate the stapes, the incudo stapedial articulation, and the facial nerve. Simultaneous abnormalities of inner ear were exceptional (1 case). CONCLUSION: High resolution CT is the best method in CAA evaluation and for guiding the planning of the surgical correction.

Regulation of T helper-B lymphocyte adhesion through CD4-HLA class II interaction.

Antigen-independent adhesion of CD4+ T lymphocytes to Epstein-Barr virus (EBV)-transformed B cells is mediated by CD2/lymphocyte function-associated antigen (LFA)-3 and LFA-1/intracellular adhesion molecule (ICAM)-1. Although some anti-CD4 antibodies block the antigen-independent adhesion of CD4+ T lymphocytes, the CD4-HLA class II interaction does not appear to significantly contribute to the forces of cell adhesion since CD4+ T cells equally bind HLA class II+ and HLA class II- mutant B cells. In addition, conjugates formed between CD4+ T cells and HLA class II- B cells remain stable for at least 1 h while CD4+T/HLA class II+ B cell conjugate percentages promptly drop off. Down-regulation of CD4 or spontaneous low expression of CD4 also results in a persistance of conjugates formed with B cells. The role of the CD4-HLA class II interaction has been further studied by investigating the inhibitory effect of synthetic 12-mer peptides analogous to HLA class II and containing the Arg-Phe-Asp-Ser sequence conserved in the beta 1 domain. These peptides were previously found to inhibit HLA class II-restricted T cell responses, this sequence being thought to be involved in CD4-HLA class II interaction. These peptides block conjugate formation of CD4+ resting T cells or clones but not of CD8+ T cells, by interacting with the T cells as shown by preincubation experiments. Down-regulation of CD4 or spontaneous low expression results in the loss of the inhibitory activity. The peptide-mediated inhibition is neutralized by a soluble dimeric CD4 molecule. Alteration within the Arg-Phe-Asp-Ser sequence results in a significant loss of inhibition. It is thus proposed that the CD4-HLA class II interaction negatively regulates antigen-independent adhesion of T cells, this interaction involving the highly conserved Arg-Phe-Asp-Ser sequence in the HLA class II beta 1 sequence as a CD4-binding site.

[Measurement of arterial pressure using 3 measurement methods in medial arterial calcification]. / Mesure de la pression artérielle par trois méthodes de mesure en présence d'une médiacalcose.

Medial calcification of the arteries, because of non-distensibility of the blood vessel walls, may overestimate the real intra-arterial pressure when blood pressure (BP) is measured by indirect sphygmomanometry cuff. In order to assess the best method for measuring BP, we compared direct intra-arterial measurements with indirect cuff sphygmomanometry as well as automatic oscillometric measurements in 15 hypertensive patients. Mean age +/- standard deviation (SD) was 62 +/- 9 years; all patients had medial calcifications of forearm and/or brachial arteries, and Osler's maneuver was negative in all. Ten sets of direct and indirect BP measurements were obtained for each patient. Results are expressed as mean +/- SD: (table; see text) There was no significant difference between cuff pressure and systolic intra-arterial pressure. The automatic oscillometric method underestimated systolic intra-arterial BP. Great individual variability was observed and could not be predicted clinically. Indirect diastolic BP values were greater than intra-arterial BP in all patients with the sphygmomanometer cuff and in 10 patients with the oscillometric recorder. There existed a direct relation between intra-arterial BP and differences between indirect BP measurements and intra-arterial BP as follows: intra-arterial BP was overestimated by indirect methods for values under 150 mmHg, and underestimated above 150 mmHg. In conclusion, invasive intra-arterial BP measurement seem to be necessary to distinguish between hypertensive and pseudo-hypertensive patients, in case of radiologic evidence of arterial calcification.

The role of lymphocyte function-associated antigen 1 (LFA-1) in the adherence of T lymphocytes to B lymphocytes.

The functional role of the LFA-1 molecule in the interaction between helper T lymphocytes and B lymphocytes was investigated using lymphocytes from patients with leukocyte adhesion deficiency, an inherited immunodeficiency characterized by a defective leukocyte expression of the LFA-1, Mac-1 (CR3) and p150,95 molecules. The ability of LFA-1- T lymphocytes to provide antigen-specific help for HLA-identical LFA-1+ B lymphocytes was reduced while their antigen-specific activation was normal. Antigen-independent conjugate formation between resting, nonactivated LFA-1- T lymphocytes and LFA-1+ B lymphocytes was impaired while LFA-1- B lymphocytes bound LFA-1+ T lymphocytes normally. Conjugate formation of activated LFA-1- T lymphocytes was mostly mediated by the CD2-LFA-3 adhesion pathway while the ICAM-1 molecule, a ligand of LFA-1, had no function. These results demonstrate that LFA-1 plays a major role in the cognate interaction between helper T lymphocytes and B lymphocytes that cannot be mediated instead by CD2 or other molecules on resting T lymphocytes.

[Use of an ion exchanger as a rapid means of extraction, applied to the determination of urinary estrogens and pregnanediol in pregnancy, using colorimetry or gas chromatography]. / Utilisation d'un échangeur d'ions comme moyen rapide d'extraction appliqué au dosage des estrogènes et du prégnandiol urinaires de grossesse par colorimétrie ou par chromatographie en phase gazeuse

The method described permits, after classical hydrolysis, extraction without a solvent of estrogens during pregnancy. It also permits estimation of pregnanediol which is eluted in a different fraction. Twenty estimations may be carried out in half a day on test samples of from 2 to 10 ml of urine. The estimation of total estrogen by colorimetry takes into consideration the efficiency of extraction by the use of a standard range treated under the same conditions. For gas chromatography, two internal standards are added to the urine after hydrolysis: these are 16,17-epiestriol and 5 beta pregnane-3 alpha, 17 alpha, 20 beta triol (PGTS) have respectively the same behaviour as estriol on the one hand and pregnanediol and pregnanetriol, on the other hand. They take into consideration resin extraction and chromatographic behaviour and may be used for quantitative estimation. The graphs of standardisation and recovery have been studied for the main estrogens together with pregnanediol. The various eluates were controlled by gas chromatography coupled to mass spectrometry.