RNA interference (RNAi) holds considerable promise as a therapeutic approach to silence disease-causing genes, particularly those that encode so-called 'non-druggable' targets that are not amenable to conventional therapeutics such as small molecules, proteins, or monoclonal antibodies. The main obstacle to achieving in vivo gene silencing by RNAi technologies is delivery. Here we show that chemically modified short interfering RNAs (siRNAs) can silence an endogenous gene encoding apolipoprotein B (apoB) after intravenous injection in mice. Administration of chemically modified siRNAs resulted in silencing of the apoB messenger RNA in liver and jejunum, decreased plasma levels of apoB protein, and reduced total cholesterol. We also show that these siRNAs can silence human apoB in a transgenic mouse model. In our in vivo study, the mechanism of action for the siRNAs was proven to occur through RNAi-mediated mRNA degradation, and we determined that cleavage of the apoB mRNA occurred specifically at the predicted site. These findings demonstrate the therapeutic potential of siRNAs for the treatment of disease.

The female gender is a risk factor for mortality in patients with Fournier's gangrene and is associated with a higher incidence of inflammation of the retroperitoneal space and abdominal cavity. Differences in male and female genital anatomy may be the reason for the rapid spread of infection to the retroperitoneum and the fatal outcome in women. Fournier's gangrene as a high-risk disease in females should attract exceeding attention.

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We have done a systematic study on the contribution of the single-stranded NCCA end (where N Is any nucleotide) to the stability of the aminoacyl stem of tRNA. A 7-bp RNA duplex with the single-strand ACCA 3' terminus derived from the aminoacyl stem of Escherichia coli tRNAA and several chemically synthesized sequence variants are characterized by proton NMR and thermodynamic parameters. The single-stranded 3' terminus noticeably stabilizes the duple in a sequence-dependent mer. Though the largest contribution to the stability gain due to the ACCA end is provided by the first dangling 3' nudeotide, the influence of even the fourth nucleotide is measurable. (7). One of these binding sites is localized in the acceptor stem; hence, we wanted to determine whether one could be detected in the acceptor-stem-derived microhelices. MATERIALS AND METHODSRNA oligonucleotides were synthesized chemically on a Gene Assembler Plus (Pharmacia) using H-phosphonate synthones according to a procedure described previously (8). The 5' and 2' OH groups of ribose were protected by 4,4'-dimethoxytrityl and tert-butyldimethylsilyl protecting groups, respectively. Protection of the exocycic amines in adenine and guanine was achieved by dimethylaminomethylene protection groups (8). The oligonucleotides were purified by HPLC on a Vydac C4 column. The RNA synthones were purchased from DIAGEN (Dusseldorf, F.R.G.). Singlestrand RNA concentrations for NMR measurements were typically 0.5-1.5 mM. The total volume of the samples was 0.5 ml. The buffer contained 100 mM NaCl and 10 mM sodium phosphate (pH 6.5). Where indicated, MgCl2 (5-7.5 mM) was added.The NMR spectra were determined on a Bruker AM 500 spectrometer operating at a proton resonance frequency of 500 MHz. To suppress the strong water signal, the 1-3-3-1 pulse sequence according to Hore (9) was applied. Chemical shifts are referenced to internal 2,2-dimethyl-2-silapentane-5-sulfonate.The UV absorbance measurements were carried out on a DU-8 spectrophotometer (Beckman) equipped with a variable-temperature unit. Absorbance at 260 nm was registered while heating 1-ml samples at a rate of 1 K/min. Single-strand RNA concentrations were 3 ,uM in all cases, and the buffer was the same as in the NMR samples. Thermodynamic parameters were determined on the basis of the two-state model from the temperature dependence of the equilibrium constant (10). RESULTS Chemical-Shift

BackgroundResection of isolated hepatic or pulmonary metastases from colorectal cancer is widely accepted and associated with a 5-year survival rate of 25–40%. The value of aggressive surgical management in patients with both hepatic and pulmonary metastases still remains a controversial area.Materials and methodsA retrospective review of 1,497 patients with colorectal carcinoma (CRC) was analysed. Of 73 patients identified with resection of CRC and, at some point in time, both liver and lung metastases, 17 patients underwent metastasectomy (resection group). The remaining 56 patients comprised the non-resection group. Primary tumour, hepatic and pulmonary metastases of all patients were surgically treated in our department of surgery, and the results are that of a single institution.ResultsThe resection group had a 3-year survival of 77%, a 5-year survival of 55% and a 10-year survival of 18%; median survival was 98 months. The longest overall survival was 136 months; six patients are still alive. In the resection group, overall survival was significantly higher than in the non-resection group (p < 0.01). Independent from the chronology of metastasectomy, 5-year survival was 55% with respect to the primary resection, 28% with respect to the first metastasectomy and 14% with respect to the second metastasectomy. A disease-free interval (>18 months), stage III (UICC) and age (<70 years) were found to be significant prognostic factors for overall survival.ConclusionOur report strongly supports aggressive surgical therapy in patients with both hepatic and pulmonary metastases from CRC. Overall survival for surgically treated selected patients with both hepatic and pulmonary metastases from CRC is comparable to hepatic or pulmonary metastasectomy. Simultaneous metastases tend to have a poorer outcome than metachronous metastases.