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Stefan Wirth

Publications and source records attributed to Stefan Wirth.

24 records · Page 2Linked to original sources
PubMed2004

C-arm-based mobile computed tomography: a comparison with established imaging on the basis of simulated treatments of talus neck fractures in a cadaveric study.

OBJECTIVE: To analyse the image quality and diagnostic effectiveness of a new C-arm-based 3D imaging method (C-arm-CT) for intraoperative evaluation of screw osteosyntheses adjacent to a peripheral joint. MATERIALS AND METHODS: Insertion of screws into four cadaveric specimens simulated the surgical treatment of talus neck fractures. Ten orthopedic surgeons and 10 radiologists evaluated X-ray, C-arm fluoroscopy, C-arm-CT and CT images. RESULTS: The best image quality was obtained with X-rays (p < 0.001), followed by C-arm fluoroscopy (2D) and CT, with the C-arm-CT (3D) being rated lowest (p < 0.001). The most correct diagnoses were obtained with CT and C-arm-CT (with no statistical difference between them), while C-arm-fluoroscopy was inferior (p < 0.001) and X-rays were the worst (p < 0.05). CONCLUSIONS: Even if the image quality of C-arm-CT is definitely inferior to that of CT, screw misplacements can be reliably detected using C-arm-CT. As compared to the current standard procedures (intraoperative fluoroscopy and postoperative radiography), C-arm-CT performed better. C-arm-CT is ideally suited to the intraoperative diagnosis of high-contrast inquiries like bone fragments and OS material, especially at the extremities. Coupling of the new 3D imaging to existing navigation systems is possible. C-arm-CT will support the further development and implementation of open and minimally invasive surgical procedures.

Bone Screws↗
PubMed2003

Functional analysis of a rare HBV deletion mutant in chronically infected children.

Liver damage caused by chronic hepatitis B virus (HBV) infection may be enhanced through the selection of deleted HBV preS mutants by intracellular accumulation of viral proteins and subsequent cell death. However, the prevalence and impact of such mutants on the clinical course of infection have not yet been studied in children. Serum samples from 60 children (mean age 9.8 y) were investigated by means of PCR and direct sequencing of the entire preS region. Only one patient (1.5%) was found with a mixed HBV population of a deletion spanning 183 nucleotides and wild-type sequences. This mutation alters the HBV large-surface protein and removes the small-surface promoter. To clarify the significance of this mutation, we studied 14 serial serum samples of the child within a follow-up of 10 y. After occurrence of the mutation, the liver enzymes increased, despite seroconversion to anti-HBe. Transfection of an HBV expression construct containing this deletion into human hepatoma cells by using an HBV in vitro replication system showed that the mutant lost the ability of nucleocapsid packaging as a result of alteration of the transmembrane topology of the large surface protein. This effect could not be restored by coexpression of wild-type large- or small-surface proteins in trans. In conclusion, the circulation of HBV preS deletion mutants is rare in childhood. However, our functional and clinical follow-up studies in one child suggest that such a mutant may have the potential to aggravate liver inflammation, especially if corroborated with larger numbers of children.

Adolescent↗
PubMed2003

Randomized double-blind study of the nutritional efficacy and bifidogenicity of a new infant formula containing partially hydrolyzed protein, a high beta-palmitic acid level, and nondigestible oligosaccharides.

OBJECTIVES: The aim of this study was to evaluate the nutritional efficacy and bifidogenic characteristics of a new infant formula containing partially hydrolyzed whey protein, modified vegetable oil with a high beta-palmitic acid content, prebiotic oligosaccharides, and starch. METHODS: In a double-blind study, healthy formula-fed term infants aged younger than 2 weeks were randomized to receive either the new infant formula (NF) or a standard formula (SF) until the age of 12 weeks. Anthropometric measurements were taken at enrollment, 6 weeks, and 12 weeks. In a subsample of infants, blood samples were taken at 6 weeks and stool samples were taken at enrollment and 6 weeks. Blood samples were analyzed for biochemical measures of protein status and amino acids, and stools were analyzed for total bacteria and bifidobacteria. Mothers completed a feeding diary and questionnaire at 6 and 10 weeks. RESULTS: One hundred fifty-four infants were enrolled in the study; 102 completed the trial. The growth of infants in both formula groups was in line with published growth curves. During the first 6 weeks, NF girls gained more weight and head circumference than the SF girls. These velocity differences were not maintained throughout the 12-week study period. The NF stools had a higher proportion of bifidobacteria at 6 weeks compared with the SF stools, and they were softer. There were no clinically significant differences in the blood biochemical and amino acid values between groups. Both formulas were well tolerated by the infants. CONCLUSIONS: When compared with a standard infant formula, the new formula supported satisfactory growth, led to higher counts of bifidobacteria in the feces, produced blood bio-chemical values typical of formula-fed infants, and was well tolerated.

Amino Acids↗
PubMed2002

Recombinant alfa-interferon plus ribavirin therapy in children and adolescents with chronic hepatitis C.

Treatment with alfa-interferon alone yielded poor results in children with chronic hepatitis C and was not generally recommended. Owing to limited experience with combination therapy in children, the aim of the study was to evaluate the efficacy and tolerability of alfa-interferon 2b in combination with ribavirin in these patients with different routes of viral transmission. In an uncontrolled pilot study, 41 children and adolescents ranging from 3 to 16 years were treated with alfa-interferon at a dose of 3 or 5 MU/m(2) 3 times weekly in combination with oral ribavirin (15 mg/kg/d) for 12 months. The mode of infection was unknown in 4, parenterally transmitted in 16, and vertically transmitted in 21 children. Forty patients completed the study. Eleven children, who remained hepatitis C virus (HCV)-RNA positive 6 months after the beginning, discontinued therapy. One boy stopped treatment because of side effects. At the end of treatment 25 patients were HCV-RNA negative (61%). All individuals remained HCV-RNA negative during the 6-month follow-up period. Nine of 15 children with parenteral (56.3%), 14 of 21 with vertical (66.6%), and 2 of 4 with unknown route of infection responded. Side effects included minor clinical signs such as fever, flu-like symptoms, anorexia, and more severe signs (21.4%) such as the development of thyroid autoantibodies and impairment of thyroid function. In conclusion, combination of alfa-interferon with ribavirin seems to be an important advance in the treatment of chronic hepatitis C in children and adolescents. This also is true for both vertically infected patients and for individuals with normal transaminase levels before therapy.

Adolescent↗
PubMed2002

Three-dimensional CT with a modified C-arm image intensifier: feasibility.

A portable C arm was modified for cone-beam computed tomography (CT). This three-dimensional (3D) CT imaging system facilitated the acquisition of fluoroscopic images during a 190 degrees rotation and computed a 3D data cube (matrix, 256 x 256 x 256; scanning time, 100 seconds) with multiplanar image reformation. The high-contrast resolution, 0.9 line pairs per millimeter, was comparable; the low-contrast resolution, minimal; and the radiation dose, 60%-80% lower, as compared with these parameters at spiral CT. The normal anatomy of small joints could be depicted, and the osteosynthesis screws in the talus were correctly identified.

Bone Screws↗