Diagnostic value of K-ras mutation analysis for pancreaticobiliary cytology specimens with indeterminate diagnosis.

Background: Fine-needle aspiration and bile duct brushing cytology have been traditionally used for early detection of pancreaticobiliary malignancy. Quite frequently, the cytological interpretations of these specimens are indeterminate. In this retrospective study, we evaluated the diagnostic value of detecting K-ras (v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog) mutation in pancreaticobiliary cytology specimens that had equivocal cytological diagnoses.

Precise DNA genotyping diagnosis of hydatidiform mole.

Objective: To estimate whether tissue DNA genotyping is effective for the confirmation and subclassification of hydatidiform moles.

Methods: Consecutive cases of products of conception were selected based on histologic alterations that are suspicious for molar pregnancy. DNA genotyping was performed by a multiplex polymerase chain reaction targeting 15 tetrameric polymorphic loci of the human genome.

Characterization of kinetics and products of the Baeyer-Villiger oxygenase MtmOIV, the key enzyme of the biosynthetic pathway toward the natural product anticancer drug mithramycin from Streptomyces argillaceus.

MtmOIV, the key oxygenase of the mithramycin biosynthetic pathway in Streptomyces argillaceus, was proven to act initially as Baeyer-Villiger monooxygenase, but may also catalyze various follow-up reaction steps. The reaction of the overexpressed pure His6-tagged enzyme with its substrate premithramycin B was studied. Various intermediates and products were isolated and physicochemically characterized, several of them being previously unknown compounds.

The complete gene cluster of the antitumor agent gilvocarcin V and its implication for the biosynthesis of the gilvocarcins.

Gilvocarcin V, an antitumor agent produced by the bacterium Streptomyces griseoflavus Gö 3592, is the most studied representative of the distinct family of benzo[d]naphtho[1,2-b]pyran-6-one aryl C-glycoside antibiotics, which show excellent antitumor activity and a remarkably low toxicity. Its biosynthesis contains many intriguing steps, including an oxidative rearrangement, the C-glycosylation, and the generation of a vinyl side chain. These steps all contribute to structural elements of the drug, which are essential for its biological activity, but only poorly understood.

Digitoxosyltetracenomycin C and glucosyltetracenomycin C, two novel elloramycin analogues obtained by exploring the sugar donor substrate specificity of glycosyltransferase ElmGT.

Our explorations of glycosyltransferase ElmGT from Streptomyces olivaceus Tü 2353, which shows an interesting flexibility regarding its sugar donor substrate, were extended toward various previously unexplored sugar co-substrates. The studies revealed that ElmGT, which normally transfers L-rhamnose to 8-demethyltetracenomycin C as a crucial biosynthetic step in elloramycin biosynthesis, is also able to process an activated non-deoxygenated sugar, NDP-D-glucose, as well as NDP-L-digitoxose, which is the first example of an NDP-L-sugar co-substrate of ElmGT possessing an axial 3-OH group. The structures of the resulting novel elloramycin analogues of these experiments, 8-demethyl-8-L-digitoxosyltetracenomycin C (4) and 8-demethyl-8-D-glucosyltetracenomycin C (7), were elucidated mainly by (1)H and (13)C NMR spectroscopy and by mass spectrometry.

Oviedomycin, an unusual angucyclinone encoded by genes of the oleandomycin-producer Streptomyces antibioticus ATCC11891.

Our investigations on the discovery of novel natural metabolites using type II polyketide synthase gene probes (actI/III) yielded an unusual angucyclinone, oviedomycin (2), when applied to the oleandomycin (1) producer Streptomyces antibioticus ATCC11891. The novel natural product was produced using S. albus R(-)M(-) as a host strain, into which a cosmid containing the oviedomycin gene cluster was transformed.

Rationally designed glycosylated premithramycins: hybrid aromatic polyketides using genes from three different biosynthetic pathways.

Heterologous expression of the urdGT2 gene from the urdamycin producer Streptomyces fradiae Tü2717, which encodes a C-glycosyltransferase, into mutants of the mithramycin producer Streptomyces argillaceus, in which either one or all glycosyltransferases were inactivated, yielded four novel C-glycosylated premithramycin-type molecules. Structure elucidation revealed these to be 9-C-olivosylpremithramycinone, 9-C-mycarosylpremithramycinone, and their respective 4-O-demethyl analogues. In another experiment, both the urdGT2 gene from S.