Publications by authors named "Petkov D"

Aneurysms of the ascending aorta, unrelated to xenobiotic administration, are described in 5 rats and 2 mice in nonclinical safety studies conducted at Charles River Laboratories (CRL) sites over the past 10 years. The most prominent microscopic finding was focal dilation with disruption of the wall of the ascending aorta with chronic adventitial inflammation or fibroplasia. The pathogenesis of this finding is unknown.

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BACKGROUND Bicuspid aortic valve is the most common congenital heart malformation, encountered in 1-2% of the population, while interventricular septal defect and patent ductus arteriosus are the most common congenital malformations associated with bicuspid aortic valve. Although bicuspid valve can have no clinical manifestation, patients with bicuspid valve are prone to develop vascular abnormalities. Aortic dilatation is the most common of these abnormalities, which in turn can lead to serious complications and often requires surgical treatment.

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Rhesus macaques are physiologically similar to humans and, thus, have served as useful animal models of human diseases including cardiovascular disease. The purpose of this study was to characterize the distribution, composition, and phenotype of macrophages in heart tissues of very young (fetus: 0.5 years, n = 6), young adult (2-12 years, n = 12), and older adult (13-24 years, n = 9) rhesus macaques using histopathology and immunofluorescence microscopy.

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Background And Aim: The problem of antibiotic resistance is worldwide and affects many types of pathogens. This phenomenon has been growing for decades and nowadays we are faced with a wide range of worrisome pathogens that are becoming resistant and many pathogens that may soon be untreatable. The aim of this study was to determine the resistance and antibiotic treatment in chronic wounds of vascular origin.

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Unilateral selective cerebral perfusion (SCP) is a method for cerebral protection in aortic arch surgery. However variations of the circle of Willis (CoW) could vitiate its protective effect. The aim of our present work was to make a retrospective analysis of 30 patients, in whom CT angio was performed between January and March 2008.

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Objectives: During unilateral selective cerebral perfusion (uSCP), with right axillary artery or brachiocephalic trunk cannulation, the brain receives blood only via the right common carotid artery and right vertebral artery (VA). The left hemisphere is perfused mainly through the circle of Willis (CW). However, at least 50% of individuals have some variation in the CW.

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Breast cancer is the most common nonskin cancer and is the second leading cause of cancer-related deaths in women. Most methods of intervention involve combinations of surgery, chemotherapy, and ionizing radiation. Both chemotherapy and ionizing radiation can be effective against many types of cancer, but they also harm normal tissues.

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Background: Avian influenza (AI) infection in poultry can result in high morbidity and mortality, and negatively affect international trade. Because most AI vaccines used for poultry are inactivated, our knowledge of immunity against AI is based largely on humoral immune responses. In fact, little is known about cellular immunity following a primary AI infection in poultry, especially regarding cytotoxic T lymphocytes (CTL's).

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The purpose of this study was to evaluate clinical protection from challenge conferred by two attenuated Salmonella enteria serovar typhimurium vaccine strains expressing the hemagglutinin (HA1) gene from a highly pathogenic avian influenza (HPAI) H5N1 (A/whooper swan/Mongolia/3/2005), under control of the anaerobically inducible nir15 promoter. Two-week-old White Leghorn chickens were immunized by oral gavage with one milliliter doses of >109 Salmonella colony-forming units once weekly for 4 weeks prior to challenge. Expression of recombinant protein was confirmed via Western blot.

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Bz(NO(2))-Orn(Boc)-OCH(2)CN was synthesized as an amino acid component with effective and successful orthogonal protection for amino acylation of 5'-O-Pivaloyl nucleosides and preparation of substrates for model ribosome reactions. The synthesis was carried out using suitable combinations of the methods of peptide synthesis and modification of amino acids.

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Enterohemorrhagic Escherichia coli (EHEC) produce one or more types of Shiga toxins and are foodborne causes of bloody diarrhea. The prototype EHEC strain, Escherichia coli O157:H7, is responsible for both sporadic cases and serious outbreaks worldwide. Infection with E.

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Infectious bursal disease virus (IBDV) is an immunosuppressive virus which primarily infects IgM B-cells in the bursa of Fabricius. Flow cytometric analysis was used to phenotype B-cell populations in the bursa and spleen following IBDV infection. In the bursa, two IgM B-cell subpopulations, designated as A and B, were identified based on cell size and granularity.

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Infections of avian influenza virus (AIV) in turkey breeder hens can cause a decrease in both egg production and quality, resulting in significant production losses. In North Carolina in 2003, a triple-reassortant H3N2 AIV containing human, swine, and avian gene segments was isolated from turkey breeder hens (A/turkey/NC/16108/03). This viral subtype was subsequently isolated from both turkeys and swine in Ohio in 2004, and in Minnesota in 2005, and was responsible for significant losses in turkey production.

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2'/3'-O-[Bz(NO(2))-Orn(Boc)]-5'-O-Piv-Ado (1) and its deoxy analog: 3'-O-[Bz(NO(2))-Orn(Boc)]-5'-O-Piv-2'-dAdo (2) were designed and synthesized as substrates for the model ribosome reaction we used to demonstrate the crucial role of A76 2'-OH of peptidyl-tRNA in the rate acceleration of peptide bond formation during protein biosynthesis.

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Unlabelled: Mitral valve repair (MVR) for mitral regurgitation (MR) has many advantages over mitral valve replacement. However, durability and reoperations after repair still remain major problems. The aim of our study was to analyze the outcome of MVR and to determine the significant risk factors for death and reoperations.

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Objectives: The optimal surgical technique for correction of left ventricular aneurysms is still debated. This study compares the midterm results achieved with linear resection or endoventricular repair.

Methods: In the period February 2002-February 2004 forty-five consecutive patients with anterior LVA have been operated.

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Characterization of field isolate 9109, Lukert, Edgar cell culture-adapted (CCA), and Edgar chicken embryo-adapted (CEA) serotype 1 IBDV strains using full-length genomic sequences is reported. IBDV genomic segments A and B were sequenced and the nucleotide and deduced amino acid (aa) sequences were compared with previously reported full-length sequenced IBDV strains. We found that the viral protein VPX and amino acid sequences between aa 202-451 and 210-473 of VP2 but not the entire VP2 protein are the best representatives of the entire IBDV genome.

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The existence of tumor formations with unidentified origin in the abdomen cavity of the pregnant can cause serious problems during the operative intervention. It is critical to find the organ origin of the existing formation and it's relations with the neighboring organs. In the following article we present some of the capabilities of the magnetic resonance tomography as a complementally to the existing in the clinical practice classical and special methods for diagnosis and differential diagnosis of tumor formations in the abdomen cavity during pregnancy.

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A computational study of 1-formyl 1,2-ethanediol aminolysis predicts a stepwise mechanism involving syn-2-OH-assisted proton transfer. The syn-oriented 2-OH takes over the catalytic role of the external water or amine molecule previously observed in 2-deoxy ester aminolysis. It provides more favorable, that is, more linear, proton transfer geometry for the rate-limiting transition state resulting in an almost billion-fold rate acceleration of the overall reaction.

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Objective: To study IL-6, IL-10, IL-12 levels and circulating immune complexes (CIC) containing IgG, IgM or IgA in sera of 14 TAO patients and 12 healthy blood donors. To evaluates the ability of TAO PBMC to produce IL-6, IL-10, IL-12, as well as to detect PBMC apoptosis after stimulation with different stimuli.

Methods: In vitro stimulation of PBMC with lypopolysaccharide (LPS), phytohemagglutinin (PHA), C3 binding glycoprotein from uscuta europea (C3bgp), pokeweed mitogen (PWM), and dexamethasone (DM) were performed.

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The possible catalytic effect of the vicinal hydroxyl group during the ammonolysis of acetylcatechol has been studied by first principle calculations. A very efficient intramolecular catalysis was found to occur when the catechol ester o-OH group is deprotonated: the activation energy of the ammonolysis decreases by 24 kcal mol(-1) as compared to that of acetylphenol ammonolysis. Using this value, the o-oxyanion-catalysed intramolecular ammonolysis was estimated to be orders of magnitude faster than the ammonolysis of acetylphenol or nonionised acetylcatechol.

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From January 2001 until December 2003 twenty patients have been operated for acute or chronic dissection with involvement of the aortic arch. 16 of them were men, and 4--women, with middle age of 57 years. Two methods of cerebral perfusion have been used--hypothermic circulatory arrest (HCA) or selective antegrade cerebral perfusion (ACP).

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