[An improved method of risk prediction and prevention of esophagogastroduodenal bleeding in geriatric urology].

With the aim of prediction and prevention of early postoperative esophagogastroduodenal bleeding (EPEGDB), 1296 elderly patients with BPH were examined during the preoperative period before isolated or simultaneous operations. Patients in group 1 (n=357) with a history of gastric or duodenal ulcer underwent esophagogastroduodenoscopy (EGDS). In group 2 (n=522) EGDS was performed and gastric acidity was determined using AGM-03 acid-gastrometer.

[The biological characteristics of Shigella flexneri strains circulating in Saint Petersburg in 1992-1994].

S.flexneri 2a strains isolated in 1992-1994 from 371 patients in sporadic cases, from 90 patients and their contacts in cases of group diseases and from 71 lethal cases of Flexner's dysentery, were studied in comparison with strains isolated in 1980s. The study revealed the biological heterogeneity of S.

[Luminescence of nucleohistone, excited in the 120-350 nm region of the spectra].

It is shown that luminescence spectra of DNA, total histone (TH) and nucleohistone (NH) are the same under UV and VUV excitation. The luminescence quantum efficiency falls with a decrease of excitation wave length to 120 nm. This effect is connected with absorption screening of aliphatic amino acids, peptide, and ribosophosphate groups (lambda < 220 nm), with photoionization of DNA (160-120 nm) and photodestruction of tyrosine in TH (lambda < 200 nm).

Vacuum UV--photophysics and photochemistry of biomolecules.

The vacuum UV radiation absorbed by biomolecules may initiate luminescence, photodestruction and photoionization processes which lead to distortions or damage of the molecular structure. To explain the mechanisms of the processes in question and the role of different molecular fragments, it is necessary to analyse the absorption spectra. The accurate determination of the photoproducts is necessary when discussing the possible scission of molecular bonds.

[Photolysis of total histone and pBr-322 plasmid DNA in the ultraviolet vacuum region of the spectrum].

The action of VUV and far UV (lambda greater than 240 nm) radiation of aqueous solutions of total histone by means of electrophoresis method is compared. By VUV photolysis the more effective destruction of HI and HIA histone fractions is determined. It may be explained by interaction of total histone with water radicals (H, OH) formed by VUV photodissociation (indirect mechanism).

[Photodimerization of uracil in films and their use for dosimetry of genetically active ultraviolet irradiation].

On the basis of the known photodimerization of uracil it is proposed to use its films obtained by sublimation in vacuum for the dosimetry of genetically active UV radiation. Experimental estimations are presented of radiation dose rate resulting in a change of uracil optical density delta D/D0 under irradiation due to photodimerization for erythemal lamp lo-30. The data obtained are used for dosimetry of lethal damage of Chlamydomonas reinhardii.

[Spectral analysis of chromatin and its components in the vacuum ultraviolet region of the spectrum].

Electronic absorption spectra of thin films of chromatin and chromatin components in ultraviolet (140-280 nm) were investigated. The absorption coefficients mu (lambda) of chromatin, nucleosomes with and without histone H1, total histones (TH), DNA were compared. The spectra of nucleosomes and chromatin differ from summary spectra of DNA + TH.

[Photo-emissions of nucleic acids and related compounds in the 120--250 nm region].

Photoemission of thin films of uracil, citosine, timine, adenine, quanine, DNA, RNA, nucleosides, nucleotides in the spectral region 125-250 nm is investigated. Photoemission work functions are determined, their values are in the interval of 5.7-6.

[Absorption spectra of nucleic acids and related compounds in the spectral region 120--280 nm].

The absorption spectra of thin films of nucleic acids, nucleosides, nucleotides, D-ribose, Na3PO4 in vacuum ultraviolet region are measured. In the spectral region 280--160 nm the absorption spectra consist of the bands of nucleic acid bases. In the range shorter than 160 nm the absorption is determined by phosphate and D-ribose groups.