Ontology-based specification and generation of search queries for post-market surveillance.

BACKGROUND: The vigilant observation of medical devices during post-market surveillance (PMS) for identifying safety-relevant incidents is a non-trivial task. A wide range of sources has to be monitored in order to integrate all accessible data about the safety and performance of a medical device. PMS needs to be supported by an efficient search strategy and the possibility to create complex search queries by domain experts. RESULTS: We use ontologies to support the specification of search queries and the preparation of the document corpus, which contains all relevant documents. In this paper, we present (1) the Search Ontology (SON) v2.0, (2) an Excel template for specifying search queries, and (3) the Search Ontology Generator (SONG), which generates complex queries out of the Excel template. Based on our approach, a service-oriented architecture was designed, which supports and assists domain experts during PMS. Comprehensive testing confirmed the correct execution of all SONG functions. The applicability of our method and of the developed tools was evaluated by domain experts. The test persons concordantly rated our solution after a short period of training as highly user-friendly, intuitive and well applicable for supporting PMS. CONCLUSIONS: The Search Ontology is a promising domain-independent approach to specify complex search queries. Our solution allows advanced searches for relevant documents in different domains using suitable domain ontologies.

Control of accommodation by longitudinal chromatic aberration and blue cones.

PURPOSE: To better understand the striking overaccommodation that is triggered at wavelengths below 430 nm (below referred to as OAB). METHODS: Fourteen students served as subjects, 6 emmetropic and 8 mildly myopic. They fixated a reading target or a Landolt C at 33-cm distance while the wavelength of light illuminating the target was varied. Their accommodation was continuously monitored with the PowerRefractor (Multichannel Systems, Reutlingen, Germany, 1995). Luminances were matched using a candela meter (Minolta LS100) and neutral density filters. The following experiments were done: (1) confirmation of the effect at 10 cd/m(2), (2) comparing 10 and 1 cd/m(2), (3) foveal stimulation, (4) parafoveal stimulation, (5) testing independent combinations of the wavelength in the center and periphery, (6) testing accommodation tonus without fixation target while the wavelength is varied. RESULTS: (1) OAB was nicely confirmed as initially described by F. J. Rucker and P. B. Kruger (2004a, 2004b) and A. Seidemann and F. Schaeffel (2002). (2) OAB remained stable at target luminances between 10 and 1 cd/m(2). (3, 4) OAB was found to be more pronounced when the parafoveal region was stimulated than when mainly the fovea was stimulated. (5) When fovea and parafovea were illuminated by light of different wavelengths, the wavelength in the foveal region had greater impact on OAB. (6) OAB was not elicited in the absence of an accommodation target. CONCLUSIONS: OAB appears to be controlled more by the parafovea than by the fovea. The findings are in line with the assumption that OAB is mediated by the short-wavelength-sensitive cones that are absent from the central fovea in most subjects.

Prevalence of thyroid nodules and carcinomas in patients operated on for renal hyperparathyroidism: experience with 339 consecutive patients and review of the literature.

The association between renal hyperparathyroidism (HPT) and differentiated thyroid carcinoma is discussed. To determine the prevalence and potential risk factors, we performed a retrospective analysis of our patients (1998-2004) and compared the data with the data from other surgical and autopsy studies. At our hospital, a total of 347 parathyroidectomies in 339 patients with renal HPT were performed. Most patients underwent preoperative ultrasound investigation of the thyroid gland and, if indicate, thyroid scintigraphy. Intraoperatively, both thyroid lobes were mobilized and palpated. Detected thyroid nodules were adequately resected and investigated histologically. A systematic analysis of the international literature was performed using the PubMed/MEDLINE system to identify publications on the prevalence of papillary thyroid carcinoma (PTC) in patients with renal HPT and in the overall population. Altogether, 133 patients (39.2%) underwent simultaneous thyroid surgery. The initial operation was hemithyroidectomy in 55 (16.2%), Dunhill operation in 36 (10.6%), unilateral subtotal resection in 17 (5.0%), bilateral subtotal resection in 5 (1.5%), and enucleation of a thyroid nodule in 18 (5.3%). A PTC was found in 8 of 339 patients (2.4%) and a follicular thyroid carcinoma in 1. Among 311 patients with primary cervical operation, 6 (1.9%) had a papillary thyroid carcinoma. All papillary tumors were classified as pT1 with a diameter of 1 to 12 mm; three were bifocal, and only one patient had positive lymph nodes. None of the analyzed factors showed a significant correlation with the occurrence of thyroid carcinoma. Depending on the screening method, the prevalence of occult PTC in European autopsy studies ranged from 5% to 9% and was markedly higher in almost all studies than in the present one. The prevalence of PTC in the present study makes an etiologic association between renal HPT and PTC unlikely. The clinical significance of these tumors remains unclear because all incidental tumors were small. However, if easily and safely feasible, relevant thyroid nodules should be removed during parathyroid surgery.

Pituitary function test and endocrine status in patient with cirrhosis of the liver before and after hepatic transplantation.

OBJECTIVE: Hormonal alterations caused by chronic liver disease are well described. In contrast, the reversibility of peripheral hormonal changes after orthotopic liver transplantation (OLT) has only partially been analyzed since the establishment of OLT as treatment of chronic hepatic failure. In addition it is not finally verified if chronic liver failure and especially hepatic encephalopathy also affect pituitary function. We therefore performed extensive endocrine studies including a global pituitary stimulation test before and after liver transplantation. METHODS: 22 patients with chronic alcoholic and non alcoholic liver failure were included in this prospective study. Basal hormone values (ACTH, cortisol, FSH, GH, IGF-I, LH, oestradiol, PRL, thyroid hormones and testosterone) were measured before and up to 5 years after OLT. Furthermore all patients underwent pituitary function tests with application of GRF, TRH, GnRH, and CRF before, 3 weeks and 3 months after OLT. RESULTS: Estradiol, LH and FSH increased significantly in postmenopausal and only slightly in premenopausal female patients after OLT. Total testosterone revealed no marked changes and was normal before and up to five years after OLT in male patients. After stimulation with GnRH the LH response in females and the FSH response in males was significantly higher three months after OLT than pretransplant. LH response in males and FSH response in females was only slightly higher after OLT. Peripheral IGF-I was low and growth hormone was elevated in all patients prior OLT. Growth hormone declined significantly three months afterwards. The response to GRF was highest prior OLT and decreased afterwards. Prolactin values were normal prior and post OLT. After stimulation with TRH prolactin values in male patients were significantly higher before OLT than afterwards. CONCLUSION: In the observed relatively small number of patients gross pituitary function in chronic liver failure remained intact, whereas slight alterations in several axis were found. These pituitary alterations are presumably only partially caused by feedback mechanisms. Both a normalisation of peripheral endocrine parameters and pituitary function were achieved by OLT despite significant alterations pretransplant.