Temperature Areas of Local Inelasticity in Polyoxymethylene.

The spectra of internal friction and temperature dependencies of the frequency of a free-damped oscillation process excited in the specimens of an amorphous-crystalline copolymer of polyoxymethylene with the co-monomer trioxane (POM-C) with a degree of crystallinity ~60% in the temperature range from -150 °C to +170 °C has been studied. It has been established that the spectra of internal friction show five local dissipative processes of varying intensity, manifested in different temperature ranges of the spectrum. An anomalous decrease in the frequency of the oscillatory process was detected in the temperature ranges where the most intense dissipative losses appear on the spectrum of internal friction.

Detection of mutant k-ras sequences in the urine of cancer patients.

DNA fragments from apoptotic cells crossing the renal barrier retain their matrix functions, which allows PCR identification of mutant sequences in excreted DNA. We investigated the possibility of detecting k-ras mutations in urinary DNA of tumor patients (colon cancer). In some patients with k-ras codon 12 mutations in tumor cell DNA the same changes were detected in the urinary DNA.

[Analysis of DNA excreted from the body as an approach to diagnosis and monitoring tumor growth].

Proceeding from their early data showing that some portion of DNA originating from apoptotic cells can enter the blood stream and pass through the renal barrier by preserving its template capabilities, the authors analyzed urine DNA from 29 patients with colorectal cancer. PCR was used to compare DNA samples from the normal mucosa surrounding the tumor and from the urine collected just prior to surgery. Six microsatellite loci were studied with oligonucleotide primers.

DNAs with unusual properties revealed by field inversion gel electrophoresis of agarose-encapsulated DNA from mammalian cells.

Distinct DNA fractions (fr-DNAs), moving separately from bulk DNA, were revealed by field inversion gel electrophoresis of DNA from intact cells lysed and deproteinized in agarose plugs. These fr-DNAs (approximately 2% of the total DNA) were ubiquitously present in nuclei of all mammalian cells studied, including human normal and tumor tissues, and showed a typical electrophoretic pattern (three bands with constant mobilities termed a-, b-, and c-DNA). Characteristic mobility shifts induced by gamma irradiation of a- and b-DNAs suggest their non-linear conformation.