Selection of twisted scroll waves in three-dimensional excitable media.

The selection of shape and rotation frequency for scroll waves in reaction-diffusion equations modeling excitable media is investigated. For scrolls with uniform twist about straight filaments, asymptotic methods are used to derive free-boundary equations at leading and first order. Both orders are validated against full solutions of the reaction-diffusion equations. Using these two orders and with no adjustable parameters, the shape and frequency of waves are correctly predicted except possibly near the point of propagation failure where the core becomes large.

Cathepsin D in normal and neoplastic thyroid tissues.

BACKGROUND: Cathepsin D is a widely distributed lysosomal acidic endopeptidase. It is an estrogen-regulated protein that is a prognostic factor in breast cancer. The aim of this study was to measure cathepsin D concentrations in thyroid tissues and to correlate these concentrations with clinical and pathologic parameters. METHODS: Cathepsin D and thyroglobulin concentrations were measured in the cytosol of normal thyroid tissues (n = 14), benign nodules (n = 6), and thyroid carcinomas (n = 32) with an immunoradiometric assay. Statistical analysis was based on the Kruskal-Wallis and Wilcoxon tests and on the Spearman rank correlation coefficient. RESULTS: The mean level of cathepsin D, expressed as picomoles per milligram protein minus thyroglobulin, was higher in the 32 carcinomas, 29.1 +/- 15.5, than in the 14 normal thyroid tissues, 8.4 +/- 2.5 (p < 0.001) or in the 6 benign nodules, 11.2 +/- 7.3 (p = 0.003). Cathepsin D concentrations correlated with tumor size; Spearman rank correlation coefficient was rs = 0.44 (p = 0.012). No significant difference was found regarding histologic type. Cathepsin D concentrations were inversely correlated with the thyroglobulin level in the tumor; Spearman rank correlation coefficient was rs = -0.60 (p < 0.001). CONCLUSIONS: Cathepsin D concentration is higher in thyroid carcinoma than in normal thyroid tissue. Increased cathepsin D concentrations correlate with thyroid tumor size but not with histologic type. Further studies should be done to confirm the potential prognostic value of cathepsin D in patients with thyroid carcinomas.

[Management of primary hyperparathyroidism in case of negative cervicotomy]. / Conduite à tenir en cas de cervicotomie blanche pour hyperparathyroïdie primaire.

Negative initial cervicotomy for primary hyperparathyroidism can be due to one of two reasons: first, one gland has not been found: it was an missing adenoma on an ectopic gland. Secondly, four normal glands were found: a missing adenoma arising in a supernumerary and ectopic gland. Successful parathyroid surgery depends the on surgeon's experience, his knowledge of parathyroid gland embryology, and his perseverance to find the pathologic gland. After an unsuccessful cervicotomy, the necessity for reoperation must be discussed. Before reexploration, diagnosis of hyperparathyroidism must be reviewed, the operative notes and pathologic report of the previous operation must be studied, and localization studies must be performed in order to define the cervical or mediastinal surgical approach.

[Arterial risks in celiosurgery]. / Risques artériels en coeliochirurgie.

It is important to recognize exceptional vascular events in celiosurgery because of their gravity. Most occur during pneumoperitoneal manoeuvres using a Palmer needle and rarely at the insertion of the first trocar. We performed a tomodensitometric study in 200 subjects free of abdominal pathology in order to determine the distance from the umbilicus to the aortic bifurcation, their projection over the spine and the superficial relations of the large vessels to the cutaneous umbilical cover. Generally, the projections of the umbilicus, and also the aortic bifurcation, lie over L4. The distance between the skin and the large retroperitoneal vesses is generally equal to one-third of the antero-posterior abdominal diameter. In thin subjects with a flat abdomen however, this distance may be smaller, even less than 3 cm. These findings emphasize the importance of "safety" manoeuvres during celiosurgery, especially during the learning period.

[Follow-up of elderly patients previously treated for uncomplicated acute lithiasic cholecystitis]. / Suivi des patients âgés, traités médicalement pour cholécystite aiguë lithiasique non compliquée.

Surgery is usually indicated in elderly patients with acute lithiasic cholecystitis although single antibiotics are often used for patients over 75 with complex medical histories and major visceral lesions. In our series of 45 patients, no new biliary pathology was seen in 26 (57.8%) after a mean follow-up of 40 months. In 15 patients, acute cholecystitis recurred and in 4 a stone found in the common bile duct. No deaths were associated with biliary pathology. While antibiotics appear to have an immediate beneficial effect, medium and long term results are mediocre. Percutaneous cholecystectomie however would be a satisfactory technique for external drainage even though mortality related to other pathologies is high.