Stefan Kröber

OBJECTIVE: The alpha(2)-Heremans-Schmid glycoprotein (AHSG; fetuin-A in animals) impairs insulin signaling in vitro and in rodents. Whether AHSG is associated with insulin resistance in humans is under investigation. In an animal model of diet-induced obesity that is commonly associated with hepatic steatosis, an increase in Ahsg mRNA expression was observed in the liver. Therefore, we hypothesized that the AHSG plasma protein, which is exclusively secreted by the liver in humans, may not only be associated with insulin resistance but also with fat accumulation in the liver. RESEARCH DESIGN AND METHODS: Data from 106 healthy Caucasians without type 2 diabetes were included in cross-sectional analyses. A subgroup of 47 individuals had data from a longitudinal study. Insulin sensitivity was measured by a euglycemic-hyperinsulinemic clamp, and liver fat was determined by (1)H magnetic resonance spectroscopy. RESULTS: AHSG plasma levels, adjusted for age, sex, and percentage of body fat, were higher in subjects with impaired glucose tolerance compared with subjects with normal glucose tolerance (P = 0.006). AHSG plasma levels were negatively associated with insulin sensitivity (r = -0.22, P = 0.03) in cross-sectional analyses. Moreover, they were positively associated with liver fat (r = 0.27, P = 0.01). In longitudinal analyses, under weight loss, a decrease in liver fat was accompanied by a decrease in AHSG plasma concentrations. Furthermore, high AHSG levels at baseline predicted less increase in insulin sensitivity (P = 0.02). CONCLUSIONS: We found that high AHSG plasma levels are associated with insulin resistance in humans. Moreover, AHSG plasma levels are elevated in subjects with fat accumulation in the liver. This is consistent with a potential role of AHSG as a link between fatty liver and insulin resistance.

BACKGROUND: Desmoplastic fibroma (DF) is an extremely rare bone tumor. The recommendations for therapy are often based on limited personal experience, and the rate of local recurrence in the published cases is very high. Therefore, an analysis of treatment results of published cases was performed. Furthermore, DNA analysis of the tumors from two patients was also performed. METHODS: The clinical, radiologic, and histologic data of two patients with DF of the long bones are presented. DNA flow cytometry was performed on both DFs, three cases of abdominal fibromatosis, and three cases of extraabdominal fibromatosis. One hundred eighty-nine patients analyzed in the literature and our own 2 patients were evaluated with regard to epidemiologic, clinical, and histologic data, with particular emphasis on treatment results. RESULTS: DNA analysis of the locally infiltrating tumors revealed indices of proliferation between 21.5% and 24%, noticeably elevated values in comparison with extraosseous desmoid tumors (8.04%). Magnetic resonance imaging (MRI) was most valuable for imaging the intraosseous and extraosseous extent of DF. The evaluation of 191 patients (189 from the literature, 2 of the authors) showed the numbers of males and females to be equivalent, with a mean age of 23 years. DF has been reported in almost all bones, with a tendency to occur in the mandible and the long bones. Approximately 12% of patients presented with a pathologic fracture (20 of 161 patients). Infiltrative growth in the soft tissue was documented in 48% of patients. Three patients developed metastases after local recurrence. Analyzing the treatment results, the authors found a recurrence rate of 55-72% after nonresection procedures, and 17% after resection. No recurrences are reported after resection with wide surgical margins. The recurrence rate of tumors of the extremities was 55%, and 25% of these patients eventually required an amputation. CONCLUSIONS: Considering the "semimalignant" character of this entity and the poor treatment results in patients with recurrent tumors, marginal or wide resection for primary treatment is recommended. The superior imaging quality of MRI greatly facilitates preoperative planning.

PURPOSE: To evaluate the size and geometry of thermally induced coagulation by using multipolar radiofrequency (RF) ablation and to determine a mathematic model to predict coagulation volume. MATERIALS AND METHODS: Multipolar RF ablations (n = 80) were performed in ex vivo bovine livers by using three internally cooled bipolar applicators with two electrodes on the same shaft. Applicators were placed in a triangular array (spacing, 2-5 cm) and were activated in multipolar mode (power output, 75-225 W). The size and geometry of the coagulation zone, together with ablation time, were assessed. Mathematic functions were fitted, and the goodness of fit was assessed by using r(2). RESULTS: Coagulation volume, short-axis diameter, and ablation time were dependent on power output and applicator distance. The maximum zone of coagulation (volume, 324 cm(3); short-axis diameter, 8.4 cm; ablation time, 193 min) was induced with a power output of 75 W at an applicator distance of 5 cm. Coagulation volume and ablation time decreased as power output increased. Power outputs of 100-125 W at applicator distances of 2-4 cm led to a reasonable compromise between coagulation volume and ablation time. At 2 cm (100 W), coagulation volume, short-axis diameter, and ablation time were 66 cm(3), 4.5 cm, and 19 min, respectively; at 3 cm (100 W), 90 cm(3), 5.2 cm, and 22 min, respectively; at 4 cm (100 W), 132 cm(3), 6.1 cm, and 27 min, respectively; at 2 cm (125 W), 56 cm(3), 4.2 cm, and 9 min, respectively; at 3 cm (125 W), 73 cm(3), 4.9 cm, and 12 min, respectively; and at 4 cm (125 W), 103 cm(3), 5.5 cm, and 16 min, respectively. At applicator distances of 4 cm (>125 W) and 5 cm (>100 W), the zones of coagulation were not confluent. Coagulation volume (r(2) = 0.80) and RF ablation time (r(2) = 0.93) were determined by using the mathematic model. CONCLUSION: Multipolar RF ablation with three bipolar applicators may produce large volumes of confluent coagulation ex vivo. A compromise is necessary between prolonged RF ablations at lower power outputs, which produce larger volumes of coagulation, and faster RF ablations at higher power outputs, which produce smaller volumes of coagulation.