Single-molecule cut-and-paste surface assembly.

We introduce a method for the bottom-up assembly of biomolecular structures that combines the precision of the atomic force microscope (AFM) with the selectivity of DNA hybridization. Functional units coupled to DNA oligomers were picked up from a depot area by means of a complementary DNA strand bound to an AFM tip. These units were transferred to and deposited on a target area to create basic geometrical structures, assembled from units with different functions. Each of these cut-and-paste events was characterized by single-molecule force spectroscopy and single-molecule fluorescence microscopy. Transport and deposition of more than 5000 units were achieved, with less than 10% loss in transfer efficiency.

Vardenafil increases penile rigidity and tumescence in men with erectile dysfunction after a single oral dose.

OBJECTIVES: To evaluate the effect of two doses of vardenafil hydrochloride on penile rigidity and tumescence while determining the pharmacokinetics. METHODS: Twenty-one patients with erectile dysfunction completed three oral single-dose regimens (placebo, 20 and 40 mg vardenafil) in a randomized, placebo-controlled, 3-way cross-over study. Penile rigidity and tumescence were measured at the base and tip with a Rigiscan for up to 2 h after dosing. The period included three 20-min repeated episodes of visual sexual stimulation. Blood samples were taken periodically up to 24 h after dosing. RESULTS: After 20 and 40 mg vardenafil, the mean duration of >60% rigidity of the base of the penis was greater than after placebo by 42.9 min (95% Cl 29.3-56.4) and by 49.3 min (95% Cl 35.7-62.9), respectively (p<0.001), and greater than after placebo by 34.6 min (95% Cl 22.1-47.1) for both doses at the tip. Additionally, significantly greater rigidity activity units and tumescence activity units were found for both doses compared with placebo (p<0.001). The plasma concentrations of vardenafil increased rapidly, with a median t(max) of about 40 min and a mean t1/2 of 4.4-4.8 h. Relative bioavailability was slightly higher for the 40-mg dose than for the 20-mg dose. The treatments were well tolerated, although slightly more adverse events, primarily headache, flushing and nasal congestion, were seen with the 40-mg dose compared with placebo. CONCLUSION: The findings confirm that vardenafil was able to generate stronger erections of longer duration than placebo under conditions of visual sexual stimulation in patients with erectile dysfunction. The pharmacokinetic, pharmacodynamic and tolerability profiles support vardenafil hydrochloride as a strong candidate for further testing as a treatment for erectile dysfunction.

Flow cytometric analysis of DNA-aneuploidy subgroups and proliferation in renal cell carcinoma.

BACKGROUND: The course of patients suffering from renal cell carcinoma varies considerably and cannot be predicted by tumor stage and grade alone. However, it is crucial to select patients with high risk of progression and to commence adjuvant immuno-chemotherapy in good time. MATERIALS AND METHODS: Multiple samples of 71 kidney tumors were studied by DNA flow cytometry. Aneuploidy was classified into subgroups employing the DNA-index. In tumors of euploid pattern and corresponding normal tissue cell cycle analysis was performed. RESULTS: 39% of tumors were found to be aneuploid. Mean proliferation fraction was distinctly higher in euploid tumors (15.6%) than in normal tissue (6.1%). DNA ploidy pattern correlated significantly (p < 0.05) with histological grading. With increasing tumor size the clonal spectrum changed as well: Tetraploid cell lines fell from 40% to 28%. The number of triploid clones rose from 33% to 56%. CONCLUSION: Based on selection of tri- and hypertetraploid carcinomas, a high-risk-group for tumor recurrence can be associated within the predominating T2/3 G2 kidney tumors. The aim is to treat these patients following curative surgery at the stage of probable micro-metastases while keeping risk of overtreatment as low as possible.

Flow cytometric DNA/cytokeratin analysis of bladder lavage: methodical aspects and clinical implications.

Over the last few years cytological investigations of bladder lavage have gained ever-increasing importance in the diagnosis and follow-up of bladder tumors. Flow cytometric DNA analysis is searching for more objective ways to characterize tumor tissue beyond its morphological differentiation. Since the end of 1987 more than 400 bladder lavages have been analyzed both cytologically and by multiparameter flow cytometry. DNA/cytokeratin-8,18 antibody labelling of methanol-fixed single cells provides a standardized method which is not liable to disturbances and enables use in a routine laboratory. Aneuploidy was divided in several subgroups according to the DNA index. Proliferation of the urothelial population as a diagnostic parameter was investigated. Multiparameter flow cytometric measurement can identify and assess all subpopulations of bladder lavage such as inflammatory cells, squamous cells and squamous cell metaplasia. Cytokeratins enable a selective examination of the urothelial population after gating; the diagnostic accuracy for aneuploid tumor stem lines is markedly increased when compared to single-parameter DNA analysis. Higher specificity is reached by excluding falsely positive 'aneuploid' squamous cells; higher sensitivity is made possible by lowering the limit of detection for actual aneuploidy within a specimen, especially for near-diploid and tetraploid carcinomas. When compared to cytological malignancy grading, the aneuploidy rate is 26% in G1/2 tumors, 42% in G2 and 78% in G3 tumors (p < 0.005). More than half of the aneuploid bladder lavages with a negative or suspect cytology were diagnosed as tumor recurrences either histologically or cytologically in the following year. Moderately differentiated carcinomas with an aneuploid DNA distribution had a higher rate of recurrence than tumors with euploid distributions when treated curatively by organ-conserving therapy. DNA/cytokeratin analysis of bladder lavage enables an artefact-free measurement of tumor criterium aneuploidy; this is more specific and less sensitive than cytology. Due to the lack of separability of urothelial proliferation in euploid specimens, the aim to make flow cytometry a method equaling cytology cannot be reached. Therefore, the greatest value of flow cytometry is not in tumor screening, but in reliable detection of highly malignant aneuploid tumors at initial diagnosis, during therapy and recognition of recurrence of superficial bladder carcinomas. Reviewing the literature, flow cytometrically proven aneuploidy, especially triploid tumor stemlines, can be used to predict possible invasive growth. DNA/cytokeratin measurements are hence indicated when an exact assessment of prognosis can influence the therapeutic procedures.

[Renal cell carcinoma--diagnosis, differential diagnosis and prognosis]. / Nierenzellkarzinom--Diagnose, Differentialdiagnose und Prognose.

OBJECTIVES: Consideration of the approach to the diagnosis and differential diagnosis of renal cell carcinoma and the criteria needed for an assessment of prognosis. MAJOR POINTS: Thanks to the comprehensive use of ultrasonography and abdominal CT, asymptomatic renal cell carcinomas confined within the renal capsule are now more often being discovered and treated by curative surgery. With the aid of ultrasonography, abdominal CT and NMR imaging, pre-operative visualization of tumor spread is now better, although, with the exception of angiomyolipoma, it is still not possible to adequately differentiate the rare benign tumors of the kidney, for example oncocytoma, from renal cell carcinomas with these procedures. The TNM classification permits a highly differentiated prognostic classification of the renal cell carcinomas. The additional prognostic parameters, triploidy and hypertetraploidy determinable by flow cytophotometry, are also considered. CONCLUSIONS: Early detection of renal cell carcinomas in an asymptomatic stage decisively influences the further prognosis, so that for all upper abdominal ultrasonographic explorations, performed for whatever reason, attention should be paid to such incidental findings.