PubMed Health⌕ Search

Biomedical subjects

N Nikolova

Publications and source records attributed to N Nikolova.

16 recordsLinked to original sources
PubMed2005

BTEX degradation by fungi.

Aromatic hydrocarbons such as benzene, toluene, ethylbenzene and xylenes (BTEX) are environmental pollutants that cause serious problems in groundwater, in surface water and in soil. Specifically, the coastal area of Bourgas bay (Bulgarian Black Sea coast) is very vulnerable to such pollution as the large petrochemical industry situated there poses a continuing threat to the environment. The potential for degradation of BTEX by fungi was studied. Two fungal strains were used in the experiments carried out in a batch reactor. The fungi were isolated from gasoline-polluted sites and were identified as deuteromycetes belonging to the Cladophialophora (CPH) and Cladosporium (CS) genera. It was found that neither of the fungal strains was able to degrade benzene. Ethylbenzene was easily degraded in all cases; o- and m-xylene were fully degraded by Cladophialophora sp. both as single substrates and in mixtures with toluene, whereas Cladosporium sp. was able to degrade them fully in mixtures with toluene only. p-Xylene was only partially degraded in all tests; however, the experiments with Cladosporium sp. showed better results compared to those with Cladophialophora sp. in this particular case. Ethylbenzene, o- and m-xylene negatively affected toluene removal rate of both fungal strains, which suggests possible competitive substrate interactions. In general, the results obtained with Cladophialophora sp. were better than those with Cladosporium sp., except in the case of p-xylene degradation.

Ascomycota↗
PubMed2004

In vitro investigation on the effect of a plant preparation with antiviral activity on the functions of mice phagocyte cells.

A polyphenol extract from the aerial roots of the medicinal plant Geranium sanguineum L. (PC) inhibited the reproduction of influenza viruses type A and B in vitro and in ovo and protected mice from mortality in the experimental influenza infection. The in vivo protective effect was connected with multiple biological activities of the preparation. The present paper focuses on the in vitro effects of the polyphenol extract on the functions of peritoneal and alveolar macrophages and blood polymorphonuclear leucocytes (PMNs), isolated from healthy ICR mice. It was found that PC in doses of 12.5 and 25 microg ml(-1) stimulated the phagocytic activity of peritoneal macrophages and blood PMNs. PC in the same doses did not significantly affect the phagocytic activity of alveolar macrophages, the migration of alveolar and peritoneal macrophages or the adherent activity of PMNs. Used in concentrations of 3.1-25.0 microg ml(-1), PC suppressed spontaneous NO production from peritoneal macrophages, while inducible NO production, provoked by LPS-, Ifn-gamma and LPS + Ifn-gamma inductions was not affected. The cell-toxic concentration of 100 microg ml(-1) increased spontaneous and LPS-inducible NO production. The experimental results demonstrated a stimulating effect of PC on the phagocytic activity of murine PMNs and peritoneal macrophages as well as a beneficial effect of the preparation on spontaneous NO production.

Animals↗
PubMed2002

Probabilistic assessment of biodegradability based on metabolic pathways: catabol system.

A novel mechanistic modeling approach has been developed that assesses chemical biodegradability in a quantitative manner. It is an expert system predicting biotransformation pathway working together with a probabilistic model that calculates probabilities of the individual transformations. The expert system contains a library of hierarchically ordered individual transformations and matching substructure engine. The hierarchy in the expert system was set according to the descending order of the individual transformation probabilities. The integrated principal catabolic steps are derived from set of metabolic pathways predicted for each chemical from the training set and encompass more than one real biodegradation step to improve the speed of predictions. In the current work, we modeled O2 yield during OECD 302 C (MITI I) test. MITI-I database of 532 chemicals was used as a training set. To make biodegradability predictions, the model only needs structure of a chemical. The output is given as percentage of theoretical biological oxygen demand (BOD). The model allows for identifying potentially persistent catabolic intermediates and their molar amounts. The data in the training set agreed well with the calculated BODs (r2 = 0.90) in the entire range i.e. a good fit was observed for readily, intermediate and difficult to degrade chemicals. After introducing 60% ThOD as a cut off value the model predicted correctly 98% ready biodegradable structures and 96% not ready biodegradable structures. Crossvalidation by four times leaving 25% of data resulted in Q2 = 0.88 between observed and predicted values. Presented approach and obtained results were used to develop computer software for biodegradability prediction CATABOL.

Biodegradation, Environmental↗
PubMed1991

[A radionuclide study of esophageal motility disorders in patients with diabetic polyneuropathy].

The radionuclide method was used to examine transport function of the esophagus in 24 patients suffering from diabetes mellitus and symmetric distal polyneuropathy. 99Tc-sulfocolloid was employed as a radiopharmaceutical agent. Radioactivity movement was visualized by means of a gamma chamber. In 9 patients (37.5%), measurements were made of the prolonged transit time for the whole esophagus as well as the prolonged transit time for the interior, median and upper third of the esophagus. The same patients demonstrated a delay of the rate of evacuation of the entire esophagus and respective parts thereof. The radionuclide method described is rapid and noninvasive. It may be included into the diagnostic complex for early identification of vegetative disorders in patients suffering from diabetic polyneuropathy.

Adult↗
PubMed1991

[Radionuclide study of disorders of esophageal motility in patients with diabetic polyneuropathy].

Radionuclide method was used to examine transport function of the esophagus in 24 patients with diabetes mellitus and symmetric distal polyneuropathy. 99mTc-+sulfur colloid was employed as a radiopharmaceutical agent. The movement of radioactivity was elucidated visually with the aid of a gamma-chamber. In 9 patients, measurements were made of the prolonged transit time of the whole esophagus as well as prolonged transit time for the lower, median and upper third of the esophagus. The same patients manifested deceleration of the evacuation of the entire esophagus and respective parts thereof. That method can be included into the diagnostic complex intended for early diagnosis of vegetative disorders in patients with diabetic polyneuropathy and for evaluating the intensity of autonomous neuropathy.

Adult↗
PubMedDate not supplied

Antibacterial diterpenic acids from Brazilian propolis.

Four labdane-type diterpenic acids and syringaldehyde were isolated and identified from Brazilian propolis. All the compounds exhibit antibacterial activity. The diterpenes, found for the first time in propolis, are typical for some Araucaria species and thus indicate a possible plant source of Brazilian propolis.

Animals↗