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Background: To evaluate the usefulness of preoperative imaging with F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) for noninvasive risk assessment of gastrointestinal stromal tumor (GIST). Materials and Methods: A retrospective review including 32 patients with pathologically proven GIST. Preoperative FDG-PET scan results including maximum standardized uptake values (SUVs) of the GISTs at 1 h postinjection (SUV1) were available for all tumors and SUVs at 2 h postinjection (SUV2) were available for 22 tumors. When both SUV1 and SUV2 were available, a retention index (RI, %) was calculated, and the correlation of these PET parameters with the histopathologic results was analyzed. Results: SUV1 was significantly higher in tumors in the high-risk group (6.0 ± 2.7) compared to those in the low risk (3.0 ± 1.6) or very low-risk (2.7 ± 1.2) groups (P = 0.009 and 0.011, respectively). At a cutoff of 5.2, the SUV1 demonstrated sensitivity of 80% and a specificity of 89% for predicting high-risk GISTs. Tumor size was significantly correlated with SUV1 (r = 0.68, P < 0.001) and SUV2 (r = 0.66, P = 0.001), and SUV1, SUV2, and RI were significantly higher in tumors with mitotic index > 5/50 high-power field than in those with lower mitotic index. RI was significantly higher in tumors with C-kit mutation than in those with no C-kit mutation. Conclusion: SUV1 measured during preoperative FDG-PET imaging correlated well with malignant potential of GISTs, especially for high-risk versus Low-/very-low-risk tumors. RI values correlated well with mitotic counts and C-kit mutation, suggesting that this mutation may have some influence on tumor metabolism
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ABSTRACT The various types of lignocellulosic biomass found in plants comprise the most abundant renewable bioresources on Earth. In this study, the ruminal microbial ecosystem of black goats was explored because of their strong ability to digest lignocellulosic forage. A metagenomic fosmid library containing 115,200 clones was prepared from the black-goat rumen and screened for a novel cellulolytic enzyme. The KG35 gene, containing a novel glycosyl hydrolase family 5 cellulase domain, was isolated and functionally characterized. The novel glycosyl hydrolase family 5 cellulase gene is composed of a 963-bp open reading frame encoding a protein of 320 amino acid residues (35.1 kDa). The deduced amino acid sequence showed the highest sequence identity (58%) for sequences from the glycosyl hydrolase family 5 cellulases. The novel glycosyl hydrolase family 5 cellulase gene was overexpressed in Escherichia coli. Substrate specificity analysis revealed that this recombinant glycosyl hydrolase family 5 cellulase functions as an endo-β-1,4-glucanase. The recombinant KG35 endo-β-1,4-glucanase showed optimal activity within the range of 30-50 °C at a pH of 6-7. The thermostability was retained and the pH was stable in the range of 30-50 °C at a pH of 5-7.