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Biomedical subjects

D Todorov

Publications and source records attributed to D Todorov.

At least 19 recordsLinked to original sources
PubMed2005

Comparative assessment of the cytotoxic effects of carboxylato-bridged dinuclear platinum (II) complexes against human tumor cell lines.

The cytotoxic effects of a series of carboxylato-bridged dinuclear platinum (II) complexes with acetate (BAP), propionate (BPP) and valerate (BVP) ligands were evaluated in a panel of human tumor cell lines. BAP proved to be the most potent antineoplastic agent, whose cytotoxic effect reached and even outclassed that of the referent drug cisplatin. This compound also exerted substantial efficacy against a broader spectrum of tumor models including the multidrug-resistant HL-60/Dox cell line. In the latter case, BAP showed lower resistance index than cisplatin. BAP was furthermore found to induce apoptosis in different cell lines as evidenced by DNA-laddering and Cell-death ELISA. Our experimental data give us reason to conclude that the dinuclear Pt(II) complex with acetate ligands is perspective for further detailed pharmacological and toxicological evaluation as an antineoplastic drug candidate.

Antineoplastic Agents↗
PubMed1998

Effect of Putrescine, 4-PU-30, and Abscisic Acid on Maize Plants Grown under Normal, Drought, and Rewatering Conditions.

The experiments were carried out with maize (Zea mays L.) seedlings, hybrid Kneja 530, grown hydroponically in a growth chamber. Twelve-day-old plants were foliar treated with putrescine, N1-(2-chloro-4-pyridyl)-N2-phenylurea (4-PU-30), and abscisic acid (ABA) at concentrations of 10(-5) m. Twenty-four hours later the plants were subjected to a water deficit program, induced by 15% polyethylene glycol (PEG; molecular weight, 6,000). Three days after drought stress half of the plants were transferred to nutrient solution for the next 3 days. The effects of the water shortage, rewatering, and plant growth regulator (PGR) treatment on the fresh and dry weights, leaf pigment content, proline level, relative water content (RWC), transpiration rate, activities of catalase and guaiacol peroxidase, hydrogen peroxide content, and level of the products of lipid peroxidation were studied. It was established that the application of PGRs alleviated to some extent the plant damage provoked by PEG stress. At the end of the water shortage program the plants treated with these PGRs possessed higher fresh weight than drought-subjected control seedlings. It was found also that putrescine increased the dry weight of plants. Under drought, the RWC and transpiration rate of seedlings declined, but PGR treatment reduced these effects. The accumulation of free proline, malondialdehyde, and hydrogen peroxide was prevented in PGR-treated plants compared with the water stress control. The results provided further information about the influence of putrescine, 4-PU-30, and ABA on maize plants grown under normal, drought, and rewatering conditions. Key Words. Maize-Putrescine-4-PU-30-ABA-Drought

Journal Article↗
PubMed1996

Comparison of three urease tests for detection of Helicobacter pylori in gastric biopsy specimens.

OBJECTIVE: To propose two modified urease tests for the detection of Helicobacter pylori in gastric biopsy specimens. PATIENTS AND METHODS: The presence of H. pylori infection was determined in 237 patients undergoing upper gastrointestinal endoscopy. Three media were used for the urease tests: Christensen's 2% urea broth and two urea agar media, modified by increasing the concentration of urea (to 4% and 10%) and phenol red and omitting the nutrients. RESULTS: The modified tests had good sensitivity (> 78%), specificity (96%) and accuracy (> or = 86%) at 2 h using small amounts (15%) of biopsy homogenates. They were statistically more sensitive and accurate than Christensen's broth. CONCLUSION: Both the modified 4% and 10% urea agar tests are simple, sensitive and specific and can be performed with small amounts of sample.

Bacteriological Techniques↗
PubMed1995

Spin labeled amino acid nitrosourea derivatives--synthesis and antitumour activity.

The synthesis of three spin labeled derivatives of N-[N'-(chloroethyl)-N'-nitrosocarbamoyl] amino acids is reported. The new nitrosoureas are obtained by condensation of the corresponding N-[N'-(2-chloroethyl)-N'-nitrosocarbamoyl] amino acid with 2,2,6,6-tetramethyl-1-oxyl-4-aminopiperidine using dicyclohexylcarbodiimide. Their chemical structures are confirmed by elemental analysis, IR, MS, and EPR spectroscopy. All newly synthesized compounds showed high antitumour activity against the lymphoid leukemia L1210 in BDF1 mice.

Amino Acids↗
PubMed1991

Nanoparticles as drug carriers for vinblastine. Acute toxicity of vinblastine in a free form and associated to polybutylcyanoacrylate nanoparticles.

The possibility of reducing toxicity of Vinblastine by fixing it in polybutyl-2-cyanoacrylate nanoparticles was studied. A significant reduction of mortality of mice was recorded after a single intraperitoneal (i. p.) injection of nanoparticle-associated Vinblastine. A wide range of doses of Vinblastine (1.04-6.25 mg/kg) were used. There was a considerable decrease of leucopenia caused by Vinblastine-loaded polybutyl-2-cyanoacrylate nanoparticles as compared to that induced by free Vinblastine.

Animals↗
PubMed1987

Immunological and radioimmunological studies in food allergy.

Experiments in order to induce food allergy were carried out in guinea pigs. The sensitization with egg albumin, pasteurized cow milk and bovine serum albumin provoked anaphylactic shock. The passive cutaneous anaphylaxis, serum antibodies, liver cytochrome P-450 concentration and the anaphylactic shock were determined. Some correlation between the mortality, anaphylactic antibodies and cytochrome P-450 monooxygenase system was established. The morphology of the jejunal mucosa, the activities of the 5 disaccharidases, the number of immunoglobulin secreting cells (Ig SC) and the mastocytes were investigated in 35 patients with food allergy. Normal mucosa was found in 28 cases as well as a significant decrease of the lactase, sucrase and trehalase activities. An increase of IgM and IgG secreting cells and of mastocytes, different electron microscopic changes in the enterocytes (an increased number of lysosomes, appearance of vesicles in cytoplasma, shortening, enlargement and uneven distribution of microvilli) as well as symptoms of functional activity in the plasmocytes and some others were also revealed. The experimental model obtained is similar to that one in humans according to the enteral way of sensitization the high selectivity of the allergic reaction which is of reagin type as the immunoglobulin changes are involved.

Animals↗
PubMed1986

Modification of the analgesic effect and the effect on body temperature of morphine and fentanyl, included in liposomal suspensions.

The analgesic and thermomodulating effect of the powerful narcotic analgesics morphine and phentanyl, included in liposomal suspensions, was tested in experiments on rats and rabbits. The aim of the experiments was to determine the changes taking place in these effects of the above analgesics, using as their carriers small neutral liposomes formed by phosphatidylcholine (egg lecithin) and cholesterol in molar ratio 7:2. The liposomes were obtained by applying the classical method of A. Bangham (1968), with subsequent ultrasoundtreatment. The changes in the body temperature of the rats and rabbits were traced in dynamics by means of electrothermometry. The analgesic activity was also investigated in dynamics, using two methods: thermal stimulation ("tail flick" test) and mechanical pressure (after Randall-Selitto, 1957). Incorporation of morphin and Fentanyl in liposomal suspensions was found to result in a tendency towards intensification and statistically significant prolongation of their thermomodulating and analgesic effects, compared with these effects of the free preparations. The pharmacological investigations carried out reveal considerable possibilities for a clinically favourable modification of the effects of the narcotic analgesics by means of their incorporation in liposomal carriers.

Analgesics↗
PubMed1986

[Mastocytes in the human intestinal mucosa].

A method has been for counting the mastocytes on 0.1 mm2 of intestinal mucosa in patients with chronic enterocolitis, gluten enteropathy, ulcerous colitis in a stage of exacerbation and in controls. The comparison of the results obtained in the separate groups of patients reveal an increased number of mastocytes in gluten enteropathy--mean = 21.01 +/- 6 as compared with the chronic enterocolitis, where mean = 9.79 +/- 3.83 (p = 0.002). Higher values of mastocytes in rectal mucosa were observed in the patients with ulcerous mucosa--mean = 15.83 +/- 4.49 as compared with the control subjects with means = 3.67 +/- 0.99 (p = 0.001). those data admit the participation of mastocytes in the morbid process in patients with gluten enteropathy and with ulcerous colitis.

Biopsy↗
PubMed1986

[Case of sarcoidosis with predominant involvement of the liver and lymph nodes].

After brief literature data, a clinical case is reported with generalized sarcoidoses with predominant affection of liver and lymph nodes. A detailed clinical-laboratory characteristics is presented and the diagnosis has been histomorphologically objectivized. The hepatocytes were electron-microscopically studied and disorders in carbohydrate metabolism established with predomination of glyconeopoiesis. Bacterial-like structures were established in hepatocytes, providing grounds to look for further possibilities in that aspect for throwing light upon the etiology of sarcoidosis. The clinical case presented confirmed the high diagnostic value of liver biopsy in sarcoidosis, even in the cases with obvious extrahepatal localization of the changes. The therapeutic effect attained confirms, once again, the therapeutic possibilities of the corticosteroids, administered in proper doses.

Biopsy, Needle↗