Genetic derangements in the tumor suppressor gene PTEN in endometrial precancers as prognostic markers for cancer development: a population-based study from northern Norway with long-term follow-up.

OBJECTIVES: The purpose of the current study was to characterize the role of PTEN in malignant transformation and to evaluate the significance of mutated PTEN exons as prognostic markers in the carcinogenesis of endometrial hyperplasia. A comparison of PTEN mutations as prognostic markers with former investigated prognosticators was also intended. METHODS: Histological material from 68 patients with endometrial hyperplasia and 10-20 years of follow-up of whom 18 later developed cancer was examined. PCR amplification and DNA sequencing were performed, screening the most frequently mutated exons 5a-8b of the PTEN gene. RESULTS: Mutations were demonstrated in 13.2% of the patients. Of the patients with cancer development, five showed to have PTEN mutations corresponding to 28%. Of the patients remaining without carcinoma, only 8% had PTEN mutations (P = 0.04). In total, there were three missense, three nonsense, and four frameshift mutations, and twice as many mutations leading to a truncated protein (six) than mutations altering one amino acid in the entire protein (three). Mutations were distributed in the following manner: three in exon 5a, two in exon 5b, two in exon 6, two in exon 7, and one in exon 8b. Only mutations in exons 6, 7, and 8a were connected with cancer development or coexisting cancer and six out of seven mutations within these exons were frameshift or nonsense mutations. CONCLUSIONS: Our results showed that mutations in the PTEN gene were statistically more frequent in cases with cancer development or coexisting cancer. Although the specificity was acceptable, the sensitivity of PTEN mutations was too low to make it suitable as a tumor marker (sensitivity of 27% and specificity of 91%) in clinical practice.

Low-loss polymeric optical waveguides with large cores fabricated by hot embossing.

A simple low-cost method of fabricating polymeric optical waveguides with large core sizes for plastic optical fibers is presented. The waveguides are fabricated by hot embossing with an ultraviolet-cured epoxy resin stamper. The stamper is fabricated by replication of a rectangular groove mold that is made from silicone rubber replicated from a ridged original silicon master. The master is fabricated by anisotropic etching of (110) single-crystal silicon. Optical waveguides with large core sizes of 100-500 microm have been fabricated, and a low propagation loss of 0.19 dB/cm at 650 nm was achieved.

Epithelium-associated bacteria in the gastrointestinal tract of Arctic charr (Salvelinus alpinus L.). An electron microscopical study.

AIMS: The primary aim was to use transmission electron microscopy (TEM) and scanning electron microscopy (SEM) to define the location of epithelium-associated bacteria in the digestive tract of the salmonid fish, Arctic charr (Salvelinus alpinus). METHODS AND RESULTS: TEM and SEM examination of the gastrointestinal tract demonstrated substantial numbers of ovoid and rod-shaped bacterial cells associated with the microvillous brush borders of enterocytes. Bacteria were found at the tips of microvilli as well as between adjacent microvilli. Endocytosis of bacteria by epithelial cells was observed in two regions (pyloric caeca and midgut). CONCLUSION: Electron microscope examination of the gut is an important tool for evaluating the microbial ecology of the fish digestive tract ecosystem. SIGNIFICANCE AND IMPACT OF THE STUDY: The results of the current study clearly demonstrate that the intestine is involved in bacterial endocytosis.

All-optical switching by use of cascading of phase-matched sum-frequency-generation and difference-frequency-generation processes in periodically poled LiNbO(3).

We show that all-optical switching is feasible by means of cascading of sum-frequency-generation and difference-frequency-generation processes under phase-matched conditions. Three-terminal switching is demonstrated experimentally with bulk periodically poled LiNbO(3). The cascading under phase-matched conditions facilitates switching with lower power than that required under phase-mismatched conditions.

Optical parametric oscillator incoherent spectroscopy.

A new incoherent Kerr shutter is demonstrated. It utilizes nanosecond optical pulses from an optical parametric oscillator (OPO) that has a broad bandwidth. Through the use of abeta-BaB(2)O(4) crystal, the OPO has a coherence time of 60-800 fs and shows wide wavelength tunability from 410 to 2600 nm. Kerr relaxation time constants for CS(2) and nitrobenzene are the same as those cited in previous works. We also show, for the first time to our knowledge, a 100-fs response for a nitrobenzene solution of 4-(N,N-diethylamino)-beta-nitrostyrene at a 740-nm idler wavelength.