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S Tsvetkova

Publications and source records attributed to S Tsvetkova.

8 recordsLinked to original sources
PubMed2003

[Is there a correlation between the vaginal colonization with group B streptococci and premature deliveries?].

The study covered 110 pregnant females during the period from January 1, 2002 till April 30, 2003. Nine females (8.18%) delivered premature newborns. Samples were taken from the posterior vaginal fornix and canalis cervicalis in the 18th and 24th gestational week. The preparations stained after Gram were examined under light microscope. Microbial cultures on blood agar were examined, too. It was established that 18 or 16.36% of all the cases presented with cultures positive for group B streptococci (Str. agalactiae) and Ureaplasma urealythicum. Some other microbial flora representatives such as Chlamydia trachomatis, Neisseria gonorrhoea and Trichomonas vaginalis were additionally identified. The independent colonization with Str. agalactiae prior to the 18th gestational week does not relate to the spontaneous abortions and premature deliveries at all. On the other hand, the colonization with Group B streptococci or their symbiosis with other microorganisms after the 23rd-24th gestational week displays a certain correlation with the premature births.

Adult↗
PubMed2002

[Association between Mycoplasma genitalium and preterm labor].

M. genitalium was identified by using polymerase chain reaction (PCR). The samples were obtained from the posterior vaginal fornix between 21-25 gestation weeks and investigated for PH, Gram Stain for bacterial vaginosis; Chlamidia trachomartis; Neisseria gonorrhoeae; Trichomonas vaginalis. Of 102 pregnant women, only five had a PCR-positive for M. genitalium. The occurrence of M. genitalium in posterior vaginal fornix at midtrimester is infrequent in pregnant women and unlikely to be a contributing factor for spontaneous preterm birth.

Animals↗
PubMed1978

Action of heparin on protein fractions of isolated nuclei and on their DNA content.

Isolated nuclei of rat hepatocytes were incubated with 0.05% sodium heparinate for 2 to 10 min. Alterations in the nuclei were controlled biochemically, determining the amounts of DNA and histones, and by cytophotometric methods determining the amounts of total and nonhistone proteins and DNA. Under the selected experimental conditions 95% of histones are bound already after 5-min incubation with heparin; nonhistone proteins of cell nuclei remain unchanged. The blockade of histones is followed by DNA diffusion into the incubation medium. Experiments with nuclear staining with alcian blue proved the specificity of heparin binding with histones and showed that heparin-histone complex remains in the nuclei, and its histones lose their extractability with 0.25 n HCl.

Animals↗
PubMed1978

Feulgen hydrolysis at refrigerator temperature.

In order to search for the better FEULGEN hydrolysis conditions, the 2 kinds of hydrolysis with 5 N HCl - at room temperature and at refrigerator temperature - were comparatively studied on rat liver imprints. 2 reactions were used: with the SCHIFF reagent binding to aldehyde groups and with methylene blue staining phosphate groups of DNA. Cytophotometry was coupled with morphological examination of stained nuclei. It was found that 1. cold hydrolysis has no substantial advantage when revealing DNA with the SCHIFF reagent but 2. it has undoubtful profit to reveal DNA, and in particular its acid-labile fraction, when staining with methylene blue. With the cold hydrolysis-methylene blue technique at least 3 categories of DNA with different acid-lability can be revealed and characterized morphologically in rat liver nuclei.

Animals↗
PubMed1977

Evaluation of Feulgen reaction performed on unfixed smears.

Feulgen reaction--both the original one with Schiff reagent and the modified one with toluidine- or methylene blue, pH = 4.0--can be carried out on air-dried smears without fixing. Hydrolysis--5 n HCl at room temperature should be 15 to 20 min for the original and 5 to 10 min--for the modified reaction. Binding of the dyes is stoichiometric in both cases.

Animals↗