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Biomedical subjects

G Ivanov

Publications and source records attributed to G Ivanov.

At least 19 recordsLinked to original sources
PubMed1999

[Surgical tactics and surgical techniques in echinococcal cysts in the lung in children].

The differentiated surgical approach to hydatid lung cysts and the operative techniques used in 343 children treated in the Department of Pediatric Surgery over 24 years (1975-1998) are presented. The left lung is involved in 143 children (41.7%), the right--in 155 (45.2%), whereas in 45 cases (13.1%) it is a matter of bilateral location. Infectious complications occur in 198 cases (57.7%). In compliance with the anatomical location, size, extent and accompanying complications two surgical procedures are mainly used: 1) Total removal of the cyst without disrupting its continuity (closed echinococcotomy) in 19 per cent, and 2) Evacuation of the cyst fluid, as well as the germinative membrane, followed by appropriate management of the residual fibrous cavity in 81 per cent of cysts. Echinococcotomy with suture obliteration of the residual cavity in conjunction with sparing lung resection, yielding superior functional results postoperatively, is the method of choice.

Adolescent↗
PubMed1998

Effect of advanced glycosylation end products on the activity of integrins expressed on U937 cells.

Advanced glycosylation end products (AGEs) are formed both in healthy old persons and diabetic patients by nonenzymatic glycosylation. However, AGEs are supposed to be a major factor in the vascular damages associated with diabetes. The aim of this study was to assess the effect of AGEs on the activity of cell adhesion molecules expressed on lymphoid cells. Human serum albumin (HSA) was glycosylated in vitro and used as a specific stimulating agent with U937 cells. The effect of glc-HSA was evaluated by the method of homotypic adhesion and adhesion to immunoplate coated with fibronectin. Specific monoclonal antibodies against integrins and ICAM-1 were applied in these studies. It was shown that glc-HSA enhanced the homotypic adhesion. The latter was mediaced via beta2-integrins as the effect was recorded after 15 min. incubation. The homotypic adhesion for the cells treated with glc-HSA followed the same kinetics as the cells incubated with phorbol myriastate acetate, which was used as a positive control. An anti-CD18 antibody inhibited the adhesion of U937 cells which indicated that the glc-HSA had a positive effect on the activity of beta2-integrins. Treatment with glc-HSA did not interfere with the adhesion of the referent cells to fibronectin coated plate. Based on these results the conclusion was drawn that the advanced glycosylation end products have a differential effect on the activity of integrin subfamilies expressed on cells of monocyte-macrophage origin.

CD18 Antigens↗
PubMed1998

The low level expression of chloramphenicol acetyltransferase (CAT) mRNA in Escherichia coli is not dependent on either Shine-Dalgarno or the downstream boxes in the CAT gene.

Recent studies have shown that the canonical Shine-Dalgarno (SD)-anti-SD interaction is dispensable for the initiation of translation of certain mRNAs in Escherichia coli. Alternative non-SD sequences (located upstream from the initiation codon) and also downstream sequences ("downstream boxes") complementary to 16S rRNA were found to be involved in the initiation of translation of mRNAs devoid of either SD or any leader sequences. In this study the chloramphenicol acetyltransferase (CAT) gene was modified to remove the 5' terminal non-translated region and/or the two potential downstream boxes in the CAT gene. Thus a series of ten CAT gene constructs was created and expressed in E. coli under a strong constitutive promoter. The results showed that CAT mRNAs devoid of both leader sequence nucleotides and the two downstream boxes in the CAT gene remained active in vivo and produced CAT protein in sufficient amounts for survival of the transformed cells at chloramphenicol concentrations up to 20-30 micrograms/ml.

5' Untranslated Regions↗
PubMed1997

Advanced glycosylated end products activate the functions of cell adhesion molecules on lymphoid cells.

It has been proposed that advanced glycosylated end products (AGEs) are involved in the pathogenesis of vascular damages in both type 1 and type 2 diabetes. Furthermore, it has been assumed that AGEs cause an alteration of both expression and activity of cell adhesion molecules which are responsible for migration of circulating cells through the endothelial layer of the vessels. The effect of AGEs on the activity of cell adhesion molecules was studied in our experiments using the homotypic adhesion assay, specific monoclonal antibodies and lymphoid cell lines. It was shown that proteins glycosylated in vitro seemed to increase the percentage of homotypic aggregation of lymphoid cells. This effect was mediated via the interaction between LFA-1 and ICAM-1 which was demonstrated by the fact that specific monoclonal antibodies against these cell adhesion molecules could block the effect of the AGEs. The results obtained reveal that the advanced glycosylated end products activate the function of cell adhesion molecules on lymphoid cells. It can be speculated that the activation of cell adhesion molecules might enhance the direct cellular contacts between the lymphoid cells in the immune response. Moreover, the effect of AGEs might be responsible for an enhanced adhesion of monocytes to endothelial cells and their migration through the vessel wall.

Antibodies, Monoclonal↗
PubMed1996

A study of pulmonary hydatid disease in children. 1. Epidemiological and clinical characteristics.

Between 1980 and 1994, 244 children (aged 1-15 years) with pulmonary hydatid disease underwent surgery at the Emergency Medical Institute 'N. I. Pirogov', Sofia, Bulgaria. The number of cases/year generally increased with time. Initial diagnosis, based on X-rays, ultrasonography and computed tomography, was confirmed by immunology. Cysts were either found in the lungs alone (178 cases) or in the lungs and the liver, spleen, kidneys, brain and/or diaphragm (66 cases). Most (61.1%) of the cases were boys and most cases (60.3%) were aged 8-15 years. Most (84.8%) had also had direct or indirect contact with dogs. The clinical manifestations were variable but the most frequent were cough, elevated body temperature, adynamia, chest pain and dyspnoea.

Adolescent↗
PubMed1993

[The results of coloesophagoplasty in childhood].

Over a six-year period (1988 through 1993), a total of 380 children with congenital and acquired esophageal diseases undergo treatment in the Second Pediatric Surgery Clinic. Plastic replacement of esophagus using a graft from the colon is performed in 31 children. The indications and procedures for colo-esophagoplasty in children are discussed. Two basic operative methods are employed--retrosternal transposition of the colon transplant (with preservation of the esophagus or in children with previous extirpation, as well as in children with esophageal atresia), or transhiatal (transabdominal) esophagectomy with simultaneous placement of the transplant into the esophageal bed. The underlying cases of early and late postoperative complications are analyzed. Emphasis is laid on the good results of the method described (operative lethality amounting to 9.7 per cent) accordingly considered as the most appropriate for children.

Adolescent↗
PubMed1991

Spectral analysis of the ECG in patients during terminal state and in the postresuscitation period.

The use of amplitude end frequency analysis of the ECG in the terminal state end postresuscitation period is presented. One hundred one studies were carried out on 64 patients in critical condition. ECG recordings were done in 3 orthogonal leads (Frank's method) with a standard amplification of 1 mV. On each lead 5-7 cardiac cycles were recorded with analysis of 2 components of the ECG: QRS complex and T wave. In order to determine the feasibility of employing such a method for forecasting pathological states, an additional 68 patients, who had been subjected to studies, were taken. In the hope of matching patterns of ECG spectral signals with indices of central haemodynamics, a group of 67 patients, who were subjected to 138 studies during the postresuscitation period, was taken. The parameters for central haemodynamics were measured by impedance cardiography with automatic analysis of the results on the EBM EC-1022. The studies carried out show that the spectral analysis of the orthogonal leads (according to Frank) brought a series of changes in the amplitude-frequency characteristics of the ECG signal in patients in the terminal state and in the postresuscitation period. The noted changes facilitate the unveiling of the disorders of the functional activity of the myocardium and the forecasting of the development of the pathological condition.

Electrocardiography↗
PubMed1990

[The effect of myosin from the human myocardium on quantitative T-lymphocyte values--active rosettes in patients with myocardial infarct and stenocardia].

The aim of the investigation is to study the influence of human myocardium myosin on the quantitative values of T-lymphocytes examined as active rosettes [correction of rosellae] in patients with ischemic heart disease. The study included 99 patients with ischemic heart disease, 49 of them with myocardial infarction and 50--with stenocardia. The controls were 61 clinically healthy donors. It was established that the active rosettes [correction of rosellae] in the patients with myocardial infarction were significantly less than in the controls (p less than 0.05). A significant inhibiting action of the human myocardium myosin on the active rosettes [correction of rosellae] was manifested (p less than 0.002). This action in the patients with stenocardia was less expressed (p less than 0.05). Myosin from a striated muscle did not exert an inhibiting action (p greater than 0.1). The results prove the participation of human myocardium myosin in the pathogenetic mechanism of T-lymphocytes suppression in patients with ischemic heart disease.

Adult↗
PubMed1990

[The cellular immunity indices of patients with a rheumatic heart defect].

In 29 patients with clinical diagnosis of rheumatic valvular disease the quantitative values of active rosettes and the specific sensitization to human heart myosin were examined. The specific sensitization to human heart myosin was examined by two methods concurrently: method of inhibiting leucocyte migration in agarose and method for direct specific lymphocytolysis with myosin. The results were compared with those of 44 clinically healthy controls. In the patients with rheumatic valvular disease (RVD) the values of the active rosettes are significantly lower (p less than 0.01) than in the healthy controls. With the method of direct specific lymphocytolysis with myosin statistically significant sensibilization of the lymphocytes to myosin was found in the patients with RVD (p less than 0.001). In 5 patients examined before and after operation it was established that 2-4 weeks after a successful correction of the hemodynamics the specific sensibilization of the lymphocytes to myosin was no more present.

B-Lymphocytes↗
PubMed1983

[Selenium content in the internal organs, musculature and blood of broiler chickens].

Experiments were carried out to establish the presence of selenium in broiler birds at different age, that had been given prophylactically selenium preparations. At the single application of such preparations selenium was found to drop in the liver, kidneys, brain, and blood, and to rise in the breast and femoral muscles. By the end of the fattening period highest was the level of selenium in the organs and tissues with the intake of sodium selenite in the drinking water; it was lowest at the injection of sodium selenite in effective amounts.

Animal Feed↗
PubMed1979

[Polarographic method of determining formaldehyde in air].

A rapid polarographic method for determination of formaldehyde microconcentrations in air has been developed. The method is highly sensitive - 0,5 cg/ml, which is 10 times higher than the sensitivity of the known methods now at use, with standard deviation less than 1.0. It is formaldehyde-selective - other saturated and unsaturated aldehydes, ketones, phenol, furfurol etc. do not interfere the determination. Sampling takes 15-20 min, polarographic analysis - 1 to 2 min. The method has been tested under conditions of production and proved to be highly reproducible and comparable with the colorimetric chromotropic acid technique.

Air Pollutants↗
PubMed1976

[Polarographic method of determining phenol in the air].

A specific, highly sensitive and exact polarographic method of phenol determination in the air is developed. The conditions of sample taking are outlined, and the effect of polarographic solution pH on the height of step and semi-wave potential is verified. The suggested method is readily applicable simple for execution, and provides for a good reproducibility and promptness of determination during productional tests.

Air Pollutants↗