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Biomedical subjects

P Petrov

Publications and source records attributed to P Petrov.

At least 19 recordsLinked to original sources
PubMed2006

Surveillance of human salmonellosis in Bulgaria, 1999-2004: trends, shifts and resistance to antimicrobial agents.

This article analyses the distribution of resistant salmonella and resistance mechanisms among the most frequently encountered serotypes in Bulgaria. Culture, biochemical tests and serotyping were used for identification. Screening for resistance to 14 antimicrobial agents with the standard Bauer-Kirbi disk-diffusion method. The double disk synergy method was used to determine production of extended-spectrum a-lactamases (ESBL). Transfer of genes coding for ESBLs with experimental conjugation. Specific primers were used for PCR detection of bla-CTX-M, bla-SHV and bla-TEM. 245 resistant salmonella strains were determined in our study; the majority originated from sporadic cases of human illness or asymptomatic infection and the remaining 23 were isolated from outbreaks. 79 producers of ESBL were detected: 5 S. Enteritidis, 1 S. Typhimurium, 9 S. Isangi and 62 S. Corvallis with types of enzymes: CTX-M3, TEM and SHV. Gene coding for extended-spectrum a- lactamases were successfully transferred into a recipient Escherichia coli C1A strain simultaneously with genes coding for resistance to aminoglycosides and sulphonamides (for bla-CTX-M3) and gene coding for resistance to aminoglycosides and chloramphenicol (for bla-SHVand bla-TEM). PCR amplification revealed bla-CTX-M3 genes in S. Enteritidis, and bla-SHV and bla-TEM in S. Corvallis. Salmonellae have revealed increasing resistance to all clinically important groups of antimicrobial agents. Bulgaria is the first country in the world where ESBL in serotype Corvallis has been reported. A wide diversity of resistance genes is found among the leading serotypes of salmonella causing human disease in Bulgaria.

Bulgaria↗
PubMed2005

Control by cytokinins of the cellular behavior in the plate meristem of zucchini cotyledons.

The temporal and spatial effects of exogenous cytokinins on both cell expansion and division activity in the plate meristem of cultured zucchini cotyledons were studied. N6-benzylaminopurine (1-100 microM) and N-(2-chloro-4pyridyl)-N'-phenylurea (4PU-30) (0.1-100 microM) greatly stimulated the cell growth and division. They provoked multiple cell cycles, formation of larger clusters of daughter cells and an increase of the final number of cells. Both cytokinins led to earlier achievement of final cotyledon size and shortened the cell doubling time. By contrast to the purine cytokinin, phenylurea cytokinin 4PU-30 enlarged the cotyledon predominantly in length. Zeatin and kinetin were less effective, particularly in stimulating cell expansion. In low concentrations, all cytokinins were more effective in stimulating division activity rather than expansion. The cells in the cotyledon margins displayed a higher division activity, especially when treated with exogenous cytokinins. The final cotyledon and cluster areas were not of the strict proportional dependence upon the number of their cells. These results provide a novel example where stimulated cell division fails to evoke a respective increase in the final organ size.

Benzyl Compounds↗
PubMed2003

[Corection of pectus excavatum with total sternal turnover].

A case of 23-year-old man with Pectus Excavatum (grade II) is reported on. The functional cardiorespiratory impairment was a leading symptom. The technique of sternal turnover with preservation of a vascular supply based on the internal mammary pedicle is introduced for the first time in Bulgaria. All procedure steps are described. Nine months after the operation cosmetic and functional results are considered excellent.

Adult↗
PubMed2002

The status of antimicrobial resistance of Helicobacter pylori in eastern Europe.

OBJECTIVE: To evaluate the primary, secondary and combined resistance to five antimicrobial agents of 2340 Helicobacter pylori isolates from 19 centers in 10 countries in eastern Europe. METHODS: Data were available for centers in Bulgaria, Croatia, the Czech Republic, Estonia, Greece, Lithuania, Poland, Russia, Slovenia and Turkey. Susceptibility was tested by agar dilution (seven countries), E test (five countries) and disk diffusion (three countries) methods. Resistance breakpoints (mg/L) were: metronidazole 8, clarithromycin 1, amoxicillin 0.5, tetracycline 4, and ciprofloxacin 1 or 4 in most centers. Primary and post-treatment resistance was assessed in 2003 and 337 isolates respectively. Results for 282 children and 201 adults were compared. RESULTS: Primary resistance rates since 1998 were: metronidazole 37.9%, clarithromycin 9.5%, amoxicillin 0.9%, tetracycline 1.9%, ciprofloxacin 3.9%, and both metronidazole and clarithromycin 6.1%. Isolates from centers in Slovenia and Lithuania exhibited low resistance rates. Since 1998, amoxicillin resistance has been detected in the southeastern region. From 1996, metronidazole resistance increased significantly from 30.5% to 36.4%, while clarithromycin resistance increased slightly from 8.9% to 10.6%. In centers in Greece, Poland, and Bulgaria, the mean metronidazole resistance was slightly higher in adults than in children (39% versus 31.2%, P > 0.05); this trend was not found for clarithromycin or amoxicillin (P > 0.20). Post-treatment resistance rates exhibited wide variations. CONCLUSIONS: In eastern Europe, primary H. pylori resistance to metronidazole is considerable, and that to clarithromycin is similar to or slightly higher than that in western Europe. Resistance to amoxicillin, ciprofloxacin and tetracycline was detected in several centers. Primary and post-treatment resistance rates vary greatly between centers.

Adult↗
PubMed2002

[One-stage operation for multi-organ echinococcosis (bilateral pulmonary, hepatic and splenic) by sterno-laparotomy].

Between 1990 and 2001 in Thoracic Surgery Department at SHATPD "Saint Sophia"--Sofia a total of 821 patients with pulmonary hydatidosis were operated on. In 5 (0.6%) of them the cysts were situated in the both lungs, lever and spleen. For the first time in the surgical practice a sterno-laparotomy were carried out for one-stage cysts' removal in this multi-organ localization. The stages of this approach as well as the indications and contraindications for its applications are described in detail.

Adult↗
PubMed2001

Geochemical investigations of sulfide-bearing tailings at Kristineberg, northern Sweden, a few years after remediation.

In the Kristineberg mining area in northern Sweden, massive, pyrite-rich Zn Cu ores are intercalated in ca. 1.9 Ga volcano-sedimentary rocks. Investigations of a tailings impoundment remediated by means of both till coverage and raising the groundwater table have been undertaken. The aim of the study was to characterise the tailings with respect to mineralogy, the chemical composition of both the tailings and the pore water, and to try to identify the significant reactions that may have occurred before and after remediation. It was found that the oxidation front had reached down to depths of between approximately 0.1 and 1.15 m before remediation. The oxidation of sulfides has produced high concentrations of some metals in the pore water; up to 26, 16, 4.1, 2.7 and 82 mg/l have been measured for Al, Mn, Fe and Zn, respectively. Concentrations of metals such as Cd, Co, Cu, Ni and Pb are lower, with average concentrations of 18.4, 83.8, 45, 79.6 and 451 microg/l, respectively. Higher concentrations of major elements such as Ca, Fe, Mn, Mg and S have been measured at depth in pore water than at shallower levels. This is probably caused by flush out of elements after remediation and vertical transport from the upper parts before remediation. The pH is relatively high, approximately 5.5 at most depths in the tailings, except in and around the former oxidation zone where it is lower, and where the highest dissolved concentrations of elements such as As, Cd, Co, Cu, Pb and Zn occur. This is probably due to the release of metals secondarily retained below the oxidation front prior to the remediation. Since the groundwater table is raised, the groundwater reaches the retained metals, which leads to desorption of metals and dissolution of secondary minerals.

Environmental Monitoring↗
PubMed2000

Mitochondrial GPx1 decreases induced but not basal oxidative damage to mtDNA in T47D cells.

The production of oxyradicals by mitochondria (mt) is a source of oxidative damage to mtDNA such as 8-oxo-dG lesions that may lead to mutations and mitochondrial dysfunction. The potential protection of mtDNA by glutathione peroxidase-1 (GPx1) was investigated in GPx1-proficient (GPx-2) and GPx1-deficient (Hygro-3) human breast T47D cell transfectants. GPx activity and GPx1-like antigen concentration in mitochondria were respectively at least 100-fold and 20- to 25-fold higher in GPx2 than Hygro-3 cells. In spite of this large difference in peroxide-scavenging capacity, the basal 8-oxo-dG frequency in mtDNA, assessed by carefully controlled postlabeling assay, was strikingly similar in both cell lines. In contrast, in response to menadione-mediated oxidative stress, induction of 8-oxo-dG and DNA strand breaks was much lower in the GPx1-proficient mitochondria (e.g., +14% 8-oxo-dG versus +54% in Hygro-3 after 1-h exposure to 25 microM menadione, P < 0.05). Our data indicate that the mitochondrial glutathione/GPx1 system protected mtDNA against damage induced by oxidative stress, but did not prevent basal oxidative damage to mtDNA, which, surprisingly, appeared independent of GPx1 status in the T47D model.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1999

Neural tissue formation within porous hydrogels implanted in brain and spinal cord lesions: ultrastructural, immunohistochemical, and diffusion studies.

A biocompatible heterogeneous hydrogel of poly [N-(2-hydroxypropyl) methacrylamide] (PHPMA), was evaluated for its ability to promote tissue repair and enhance axonal regrowth across lesion cavities in the brain and spinal cord in adult and juvenile (P17 P21) rats. Incorporation of PHPMA hydrogels into surrounding host tissue was examined at the ultrastructural level and using immunohistochemical techniques. In addition, and in parallel to these studies, diffusion parameters (volume fraction and tortuosity of the gel network) of the PHPMA hydrogels were evaluated pre- to postimplantation using an in vivo real-time iontophoretic method. The polymer hydrogels were able to bridge tissue defects created in the brain or spinal cord, and supported cellular ingrowth, angiogenesis, and axonogenesis within the structure of the polymer network. As a result, a reparative tissue grew within the porous structure of the gel, composed of glial cells, blood vessels, axons and dendrites, and extracellular biological matrices, such as laminin and/or collagen. Consistent with matrix deposition and tissue formation within the porous structure of the PHPMA hydrogels, there were measurable changes in the diffusion characteristics of the polymers. Extracellular space volume decreased and tortuosity increased within implanted hydrogels, attaining values similar to that seen in developing neural tissue. PHPMA polymer hydrogel matrices thus show neuroinductive and neuroconductive properties. They have the potential to repair tissue defects in the central nervous system by replacing lost tissue and by promoting the formation of a histotypic tissue matrix that facilitates and supports regenerative axonal growth. () ()

Animals↗
PubMed1999

[Post-cystectomy derivations - a rule or control of technical skills?].

Limitations in gaining better understanding of bladder tumor responsiveness do exist, and accordingly the therapeutic interventions undertaken in diverse forms of the disease are conspicuous for discrepancies (M. J. Droller, 1990). E. Bricker in 1950 is the first to practically implement ileal conduit for urine derivation, and thus initiates the new and newest continent derivations. Over the period 1992-1998, in the Chair of Urology are performed 76 cystectomies with different urine derivations, using seven methods for the purpose: [table: see text] Also discussed are the conditions a derivation should mandatorily meet. Emphasis is laid on the fact that the choice of derivation is still largely dependent on the skill and experience of urologists.

Adult↗
PubMed1998

Increased endothelial cell expression of platelet-endothelial cell adhesion molecule-1 during hyperoxic lung injury.

Lung injury is a frequent consequence of oxygen (O2) therapy administered to newborns and adults with respiratory distress. Acute exposure to hyperoxia results in a well-described pathophysiologic response in the lungs. Because inflammation is an important component of pulmonary O2 toxicity, we have an interest in identifying the inflammatory mediators that increase during hyperoxia. Platelet-endothelial cell adhesion molecule-1 (PECAM-1), a member of the immunoglobulin superfamily that is expressed at the junctions between endothelial cells, is essential to the transendothelial migration of leukocytes. We hypothesized that increased expression of PECAM-1 occurs in pulmonary endothelial cells during hyperoxic lung injury. Adult mice were exposed to 100% O2 for up to 96 h. We analyzed PECAM-1 expression by RNA blot hybridization, in situ hybridization, and immunohistochemistry. A increase in PECAM-1 mRNA was seen as soon as 2 d of hyperoxia relative to unexposed control mice. PECAM-1 mRNA and protein were found in endothelial cells of both large and small arteries. The expression of PECAM-1 in capillary vessels was further confirmed using in situ hybridization at the electron microscope level. This increase in PECAM-1 expression coincided with the appearance of leukocytes in lung tissue. These observations suggest that PECAM-1 expression is a relatively early step in the inflammation cascade, and intervention at this phase may be critical to the prevention of further damage.

Alternative Splicing↗
PubMed1998

[The significance of congenital inhibitor deficiency in acute pancreatitis].

In the past few years, genotype influence on the occurrence and developmental course of acute pancreatitis is ever more frequently accounted for. Forty-three patients presenting mild (2), medium-severe (33) and severe (6) form of the disease are covered by the study, undertaken with the purpose to assay the role played by some immunoglobulins and polymorphic plasma proteins in this particular disease. In evaluating plasma proteins a deficit of the protease inhibitor Alpha1 antitrypsin is found in twelve patients. However in two cases only Alpha1 antitrypsin deficit is associated with deficiency of the other protease inhibitor--the Alpha2 macroglobulin. In acute pancreatitis patients a genetically determined deficit of protease inhibitory activity is documented, considered a good reason to undertake conservative management using protease inhibitors in the initial phases of the condition.

Acute Disease↗
PubMed1998

[Intra-arterial therapy as a treatment method in acute pancreatitis].

Intra-arterial therapy has a definite place in the complex management of pancreatitis. Drug infusion into the celiac trunk and a. mesenterica superior is a procedure bringing about the highest concentration (16-18 times) in the pathological focus (Briskinikol), inactivation of vasoactive and toxic products, interference with autolysis of the gland, allowing in turn the administration of smaller drug amounts. Intraarterial therapy (IT) is carried out in 18 patients presenting destructive pancreatitis: total necrosis--2, focal necrosis--8 and hemorrhagic pancreatitis--8, with ages ranging from 25 to 65 years, in a poor general condition. IT is conducted after catheterization of truncus celiacus and celiacography, with infusion effected through single time introduction of 0.5 per cent novocain solution, heparin, kontrikal, Petphtoruracil, antibiotic and atropine.

Acute Disease↗
PubMed1997

The effects of tracheal occlusion and release on type II pneumocytes in fetal lambs.

UNLABELLED: Fetal tracheal occlusion (TO) has been shown to lead to lung hyperplasia in various animal models, and this procedure has already been carried out in human fetuses with congenital diaphragmatic hernia (CDH). However, the authors previously showed that TO caused a decrease in type II pneumocytes. PURPOSE: The aim of this study is to examine the effects of TO and release on type II pneumocytes. METHOD: To was carried out with a Swan Ganz or Fogarty catheter in fetal sheep at 116 to 118 days of gestation. TO was maintained for 2 weeks followed by deflation of the balloon for 1 week before delivery, in group 1; in group 2, TO was maintained for 19 days and released 2 days before delivery. Group 3 consisted of previously reported animals who had TO maintained until birth. Unoperated twins served as controls. All specimens were analyzed using the surfactant protein C (SP-C) mRNA as a specific marker for type II pneumocytes. We used Northern Blot and in situ hybridization techniques to quantify total SP-C and the density of type II cells. Electron microscopy (EM) was also used to evaluate and quantitate type II cells. RESULTS: TO resulted in significant lung growth in all groups. In situ hybridization and Northern Blot analysis showed that there was a complete recovery of type II cells in group 1 versus controls. Quantitative EM analysis confirmed these findings. In group 2 the number of type II cells was decreased but there was an increase in SP-C content per type II cell versus group 3. CONCLUSION: Lung growth after TO appears to occur at the expense of type II cell differentiation. This effect is reversible with the release of TO before birth in this animal model.

Airway Obstruction↗
PubMed1997

Deleterious effect of tracheal obstruction on type II pneumocytes in fetal sheep.

It was previously shown that tracheal obstruction accelerated fetal lung growth and eventually reversed the pulmonary hypoplasia in experimental diaphragmatic hernia. We have successfully developed a reversible tracheal obstruction technique in fetal sheep using balloon occlusion and showed that 3 wk of obstruction induced significant lung growth of the same magnitude as the tracheal ligation. The purpose of this study was to examine the effects of 1 and 3 wk of tracheal occlusion on the alveolar cell population with specific attention to the type II pneumocytes. We first showed that 1 wk of occlusion induced a significant increase in lung weight and in alveolar surface area. We then used the surfactant protein C (SP-C) mRNA as a specific marker of differentiated type II pneumocytes. Total RNA was isolated from fetal sheep lung with or without tracheal occlusion, and Northern blots were hybridized with a cDNA probe specific for the sheep SP-C. The results show a dramatic decrease in SP-C mRNA expression (8.8-fold, p < 0.01). In situ hybridization showed a marked decrease in the density of cells expressing SP-C, as well as the amount of SP-C mRNA expressed by the cells. The effect was present as early as 1 wk of occlusion. The sparseness of type II pneumocytes was further confirmed by electron microscopy. We thus conclude that tracheal obstruction causes a profound decrease in the number of type II pneumocytes in the lungs. Given the crucial role of type II pneumocytes in surfactant production, we could speculate that, if tracheal occlusion is able to accelerate lung growth, the final product is probably surfactant-deficient.

Airway Obstruction↗
PubMed1997

[The surgical treatment of pancreatic pseudocysts following acute pancreatitis].

The tactics and results of the operative treatment of pancreatic cysts, complicating severe destructive pancreatitis in a series of thirteen patients, are discussed. The following operative methods are made use of: marsupialization (1), Yurash (10), cystojejunoanastomosis with Braunova (2). The character and scope of surgical intervention are determined intraoperatively, depending on the anatomical situation faced. In pancreatic cysts operated according to Yurash (cystogastroanastomosis), an original drainage method with two probes introduced nasally is used--one wider into the anastomosis, and a narrower one into the duodenum for feeding. The probes are retained for periods ranging from 9 to 35 days. No relapse of the cysts operated by different methods are registered, with the exception of a female patient undergoing marsupialization. In one case operated according to Yurash where no preoperative preparation is done the outcome is fatal, with the patient dying of hemorrhage on the third postoperative day. All patients are operated within 3 months after the formation of cysts. The preoperative preparation includes Kontrikal, Petphtoruracil, atropine, heparin and antibiotic; in some patients the listed drugs are introduced intraarterially into truncus celiacus. A number of inferences are reached and recommendations made: 1. Waiting for the generally accepted 3-month term is unnecessary. 2. In cysts involving the head of the pancreas, tightly adherent to the posterior wall of the stomach, the method of Yurash with the modification suggested for probing should be given preference. 3. In cysts of the body region and tail cystojejunoanastomosis with Braunova is practicable. 4. Proceeding with the preoperative medication in the postoperative period is advisable.

Acute Disease↗
PubMed1997

[Genetic susceptibility to pancreatitis].

Pancreatitis is a complicated polyetiological disease rather frequently met with. Inflammatory degenerative changes in the pancreas are the underlying cause of the condition which in acute cases may give rise to irreversible pancreonecrosis, and in chronic ones--to fibrosis development and severe pain syndrome. Of utmost importance is the patient's genetic susceptibility to pancreatitis. The purpose of the study is to assay the role of genetic factors involved in the etiopathogenesis of pancreatitis. The interest focused on alpha1 antitrypsin (alpha 1 AT) arises from the fact that its mutant forms are implicated in the destructive processes within the organism. The reduced inhibitory activity of alpha 1 AT enhances the action exerted by the proteolytic enzymes--trypsin and chymotrypsin [correction of hemotrypsin]. Impairment of the balance between proteases and their inhibitors plays certain role in pancreatitis development. Seventy patients, 44 men and 26 women, are covered by the study, with 42 of them presenting acute pancreatitis, and 28--chronic relapsing form. A high rate of alpha 1 AT mutant genes carrier state is established--14.28 per cent, exceeding statistically significantly the incidence of alpha 1 AT variants in the Bulgarian population--4.95 per cent (p < 0.01). In acute pancreatitis patients the incidence of alpha 1 AT variants is 2.38 per cent, and in chronic forms--32.14 per cent. In pancreatitis patients alpha 1 AT deficit brings about genetic predisposition to serious complications, e.g. chronification of the process. Individual therapeutic approach is mandatory, with Kontrikal used in chronic relapsing pancreatitis in the form of substitutive medication, and in acute pancreatitis--according to judgement depending on the clinical picture and laboratory findings.

Acute Disease↗