PubMed Health⌕ Search

Biomedical subjects

S Nikolova

Publications and source records attributed to S Nikolova.

At least 19 recordsLinked to original sources
PubMed2001

Arthritis after experimental infection with Yersinia enterocolitica 0:3 in rabbits.

Arthritis in rabbits was caused after experimental oral infection with Yersinia enterocolitica (serotype 0:3, biotype 4, pYV+). Clinical and laboratory signs, bacterial dissemination to the viscera, immune response and morphological findings were studied from day 1 to day 40 post-infection (p.i.). Augmentation of body temperature and erythrocyte sedimentation rate occurred on day 1, and on day 8 p.i. was accompanied by leucopenia. The number of alveolar macrophages was increased up to the 15th day p.i., in contrast to peritoneal macrophage numbers. Extensive bacterial colonization of the internal organs was detected at necropsy until the end of the experiment. Analysis of the cell immune response revealed activation of B cells in peripheral blood, spleen and thymus as well as augmentation of T-cell number in the lymphoid organs examined on days 15, 28 and 40 p.i. Histological changes typical of a generalized infection, such as purulent meningoencephalitis, catarrhal pneumonia and lymphadenitis, were observed. Clinical and morphological manifestations of arthritis were also established. The results obtained show that Y. enterocolitica (serotype 0:3, pYV+) induces a generalized, non-lethal infection in Chinchilla rabbits, complicated by arthritis.

Animals↗
PubMed2001

Pretreatment of guinea-pigs with iron or desferal influences the course of Yersinia enterocolitica infections.

The effects of iron excess and desferrioxamine in pretreated guinea-pigs on the immune response (production of Yops) and on the histological changes in infections with Yersinia enterocolitica 0:3 and Y. enterocolitica 0:8 were investigated. The prior overload of the guinea pigs with Dextrofer or treatment with Desferal increased the pathogenic activity of Y. entercolitica 0:3 and led to a generalized infection. Immunoblot analysis showed that in conditions of iron overload the expression of outer membrane proteins (Yops) of Y. enterocolitica 0:8 was blocked. This was accompanied by weak changes in the tissues. The iron limited conditions stimulated production of a low molecular weight protein (17 kDa) on day 6 and easier proliferation of the bacterium. This in vivo study intends to show that in Y. enterocolitica infections a leading role is played not only by iron itself but also by the bacterial strain.

Administration, Oral↗
PubMed2001

Isolation of pathogenic yersiniae from wild animals in Bulgaria.

Pathogenic Yersinia strains were isolated between December 1998 and April 1999 from 37 wild animals: rabbit (Lepus europeus), boar (Sus scrofa scrofa), asiatic jackal (Canis aureus), red fox (Vulpes vulpes), mouflon (Ovis musimon), european river otter (Lutra lutra), beech marten (Martes foina), polecat (Musleta putorius) and wild cat (Felis silvestris). It was established that among the wild animals Y. enterocolitica strains of serotype 0:3 predominated, accompanied by Y. pseudotuberculosis strains of serotype 0:3. In one sample from asiatic jackal and one sample from rabbit, Y. enterocolitica serotype 0:8 was isolated. Yersinia enterocolitica and Y. pseudotuberculosis strains were isolated from tonsils and tongues as well as from the viscera--lung, liver, heart, spleen, kidney and lymph nodes, mainly in young animals (1-2 years of age). The results showed that wild animals are a possible natural reservoir for pathogenic Y. enterocolitica and Y. pseudotuberculosis and are included in the epidemiological chain of yersinioses.

Animals↗
PubMed2000

Treatment of adjuvant arthritis in mice with yeast superoxide dismutase.

Yeast Cu/Zn superoxide dismutase (SODy) was used for treatment of adjuvant-induced arthritis in mice. SODy was applied intraperitoneally (i.p.) in doses of 10 mg/kg (30,000 U/kg) and 30 mg/kg (90,000 U/kg) one or three times daily on consecutive days. It was very effective in reducing the paw swelling whether administered before or immediately after induction or when the treatment began at the onset of inflammation or at the peak of the arthritic process. The effect of yeast SOD was compared to that of commercial SOD from bovine erythrocytes (SODb), as well as with indomethacin treatment. Histological data confirmed the antiinflammatory effect of yeast SOD. The schedules and doses tested did not elicit anti-SOD antibodies in serum.

Animals↗
PubMed1998

Studies of Yersinia enterocolitica 0:3 experimental infection in pigs.

Y. enterocolitica (serotype 0:3, pYV+, biotype 4) infection of 20-day-old pigs challenged per os with a total dose of 5 x 10(10) CFU was studied. Clinical, paraclinical and morphological findings were examined in dynamics from 1st to 25th days post infection (p.i.). Augmentation of body temperature and erythrocyte sedimentation rate during the first days p.i. were established. The number of leucocytes, peritoneal (pMa) and alveolar (aMa) macrophages was increased significantly from 4th to 15th days p.i. Phagocytic activity of pMa and aMa examined in vitro was maximal on days 15 and 25 p.i. The enhanced phagocytic activity of macrophages was in correlation with the observed histological changes--purulent meningoencephalitis, necrotic tonsillitis, peribronchial lymphoid-leucocytic cell infiltration and catarrhal enteritis. Extensive colonization of internal organs was detected at necropsy till the end of trial. Analysis of the results shows that this orally caused infection runs slowly with dissemination and persistency of Y. enterocolitica 0:3 in the macroorganism, like a generalized infection.

Animals↗
PubMed1998

Experimental mixed infection with Yersinia enterocolitica and Listeria monocytogenes in guinea pigs.

The pathogenesis and the cell immune response (CIR) of guinea pigs after mixed infection with Y. enterocolitica and L. monocytogenes was investigated. The guinea pigs were infected per os with 1.1 x 10(9) CFU Y. enterocolitica 0:3, (pYV+) and four days later with 1.1 x 10(9) CFU L. monocytogenes 4B. Clinical, paraclinical and morphological findings attending the infectious process were followed in dynamics up to the 28th day post infection (p.i.) with L. monocytogenes. The phagocyting activity of alveolar macrophages (aMa) was suppressed against Y. enterocolitica, in contrast to peritoneal macrophages (pMa) engulfing yersiniae more actively at the end of the study. Moreover, the tendency of augmented entering in both phagocytes of L. monocytogenes cells was well demonstrated, starting at the earlier intervals of examination. Histopathological studies showed a purulent meningoencephalitis and a catarrhal pneumonie, non-reactive micronecroses in the spleen and lymphadenitis catarrhalis in the mesenteric lymph nodes. Analysis of the T-cell immune response (T-CIR) showed maximal values in the spleen lymphocytes after Y. enterocolitica and L. monocytogenes mixed infection. The B-CIR occurred early (at the 7th day p.i.) and was maximal at the 28th day p.i. in blood lymphocytes. The results obtained demonstrated that the mixed infection of guinea pigs with Y. enterocolitica and L. monocytogenes runs has a non lethal, generalized illness with a dominant role of L. monocytogenes cells.

Animals↗
PubMed1997

Immunological and electronmicroscopic studies in pigs infected with Yersinia enterocolitica 0:3.

The cellular immune response after an experimental oral infection with Yersinia enterocolitica (serotype 0:3, biotype 4, harbouring the virulence plasmid-p YV) was studied in pigs. A maximal stimulation of the T cell population in the thymus, spleen and peripheral blood was stated on the 15th day post infection (p.i.) by the rosette forming cell (RFC) test. The hemolysins (produced by B cells and detected by the plaque forming cell test-PFC) were significantly increased on the 15th day p.i. among the thymus and spleen lymphocytes and on the 25th day p.i. among the blood lymphocytes. Blood and thymus lymphocytes were activated faster by the infectious agent in comparison to the spleen cells. The electronmicroscopic studies revealed an intracellular presence of the bacteria in alveolar macrophages (aMa) and peritoneal macrophages (pMa) as well as in Peyer's patches and tonsils as early as on the 4th day p.i. Extracellularly located bacteria were observed, too. The results have shown that inspite of the activation of T and B cell immune response, this infectious agent persisted in the porcine organism.

Animals↗
PubMed1997

Cell wall-deficient forms (L-forms) of Listeria monocytogenes in experimentally infected rats.

Experimental infections were induced with different bacterial forms of Listeria monocytogenes: parental (S-forms), protoplastic (L-forms) and combined inoculum of both forms by i.p. injection of rats. The parental bacterial forms (S-forms) were isolated up to 7 days after challenge from the peritoneal cavity and the liver, while the L-forms were isolated up to 60 days from the peritoneal cavity. Continuous adhesion of L-forms on the peritoneal macrophage surface was found by scanning-electron microscopy. Erythrocyte and leucocyte count as well as some clinical chemistry parameters were measured during infections. They showed different dynamics in the three experimental groups. Histomorphological changes in the liver (microabscesses and mononuclear cellular granulomas) of infected animals were observed. They were less intensive and appeared later in rats infected with L-forms. The experiments demonstrated that infections caused by parental bacterial forms and by combined inoculum took an acute course, while the infection caused by L-forms could be distinguished as a prolonged and persistent one.

Animals↗
PubMed1996

Experimental melioidosis in inbred mouse strains.

Experimental infection was induced in three inbred mouse strains (BALB/c, BDF1 hybrid and C57BL) by i. p. inoculation with Pseudomonas pseudomallei. The bacterial load in the viscera and the host response induced in different compartments (blood, peritoneal cavity and organs) were determined. Blood cell parameters and peritoneal exudative cell populations were evaluated during the infection with the aid of an automated haematology analyser Technicon H-1. It was found that all mouse strains produced a similar intraperitoneal inflammatory response with predominance of granulocytes at the early stage of infection and subsequent increase of macrophages especially in BDF1 hybrid and BALB/c mice. The highest bacterial count found in the liver and spleen of C57BL was associated with corresponding tissue damage (purulent pneumonia, abscesses in liver, karyorrhexis of hepatocytes and meningoencephalitis). The degree of bacterial load and histological changes found in BALB/c and BDF1 hybrid mice were lower than in C57BL mice. The results show that the variations in the infection magnitude among inbred mouse strains are host-dependent.

Animals↗
PubMed1996

Experimental melioidosis in hens.

Experimental intramuscular infection of hens with Pseudomonas pseudomallei, strain 2796 (1 x 10(9) CFU from a 24-h culture) was reproduced. Clinical, paraclinical and pathomorphological findings were followed from 1 to 30 days after challenge. Haemagglutinin titre, bacterial dissemination in the viscera, number of leucocytes, alveolar (aMa) and peritoneal (pMa) macrophages and their phagocytic activity in vitro were studied. During the course of infection a leucocytosis as well as an increased haemagglutinin titre (1:256) were established. The number of bacteria per gram tissue in the spleen and liver was highest at 1 day post-infection (p.i.). Melioidose bacteria from egg yolk were isolated at 15 and 30 days p.i. Leucocyte and pMa phagocytic activity was maximal at 3 days p.i. unlike the activity of aMa which increased gradually until the end of the study. Inflammatory-necrotic changes were found in the viscera and brain at 3 and 15 days p.i. The investigation of experimental melioidosis infection in hens showed that they are susceptible to P. pseudomallei and this disease takes a generalized subacute course.

Animals↗
PubMed1994

Responsiveness of susceptible inbred mice to Yersinia pseudotuberculosis serovar III infection.

The susceptibility of BALB/c, C57BL and BDF1-hybrid mouse strains to Yersinia pseudotuberculosis serovar III infection was studied. The bacterial load in the viscera and brain and the host responses at different levels, i.e. blood, peritoneal cavity and organs were determined. Blood cell parameters and peritoneal exudate cell population were evaluated during the infection using the automated hematologic analyzer Technicon H-1. It was found that BDF1-hybrid mice produced an early peritoneal inflammatory response, while in BALB/c and C57BL mice it was not observed. The high susceptibility of C57BL was associated with a great number of microorganisms in the organs and with the corresponding histological changes. It was shown that the magnitude of the inflammation induced by Y. pseudotuberculosis varied among the host strains used. The variations of the susceptibility to Y. pseudotuberculosis among inbred mouse strains suggest the possible role of genetic factors regulating the host defence.

Animals↗
PubMed1993

Role of iron in pathogenesis of guinea pigs infected with Yersinia enterocolitica 0:3.

Examined have been the pathogenesis of guinea pigs preliminarily overload with iron, and infected with Yersinia enterocolitica 0:3 in a logarithmic and stationary phase of development, cultivated at 25 degrees C and 37 degrees C. Dextrofer-100 (Fedex-100) medicine have been used as an iron source. The results show that in spite of the phase of development and cultivation temperature, the iron excess does not increase the bacterial virulence of the strain used so far. The morphological changes in the mesenterial lymphatic nodes, small intestines, spleen and liver of guinea pigs treated with iron, and then, infected with Y. enterocolitica, are more slightly expressed as compared with animals infected with Y. enterocolitica only. The investigations suggested so far, have attested that Yersinia enterocolitica 0:3 does not contain a gene responsible for the synthesis of the protein participating in iron uptake.

Animals↗
PubMed1992

Cytometric and cytochemical study of peritoneal and alveolar macrophages from Yersinia pseudotuberculosis infected ground squirrels (Citellus citellus).

The enzymic activity (succinate dehydrogenase, acid and alkaline phosphatase) of alveolar and peritoneal macrophages as well as leucocytic reaction of ground squirrels infected with Yersinia pseudotuberculosis (I and III serovar) have been investigated in dynamics from the 1st up to the 30th day. The animals infected with III serovar survived only to the 7th day, while those infected with I serovar survived up to the 30th day after inoculation. A massive influx of leucocytes having peak values (100-fold increase) on the 3rd day after infection has been found in the peritoneal cavity of the animals infected with I serovar. Moderate leucocytosis in the blood, and insignificant fluctuations in alveolar macrophage number have been established too. An earlier and higher activation of succinate dehydrogenase in alveolar and peritoneal macrophages from animals infected with III serovar in comparison with those infected with I serovar was observed. No differences in alkaline phosphatase activity of alveolar and peritoneal macrophages have been found between the animals infected with I and III serovar. A correlation has been found between the number of leucocytes and changes in the enzymatic activity of the macrophages. A metabolic transformation was demonstrated typical for different macrophages (peritoneal and alveolar), in the course of this experimental intraperitoneal infection. Obviously, more virulent serovar III of Y. pseudotuberculosis fails to attract leucocytes to the peritoneal cavity sufficiently quickly, so it overcome the local protective mechanisms with consequent systemic cytochemical changes. On the other hand the virulent serovar I attracts leucocytes to the peritoneum and is presumably destroyed by them.

Animals↗
PubMed1990

[Percutaneous cholecystectomy and litholysis with methyl tert-butyl ether under ultrasonic control].

The first percutaneous cholecystostomies under ultrasound control with therapeutic purpose, performed in Bulgaria, are reported. They furnish the opportunity for local treatment of acute cholecystitis and chemical litholysis in biliary calculosis. Control of the latter was realized by microscopic determination of the amount of cholesterine crystals in periodically aspirated bile. Indications for this procedure are defined after thorough discussion by internist and surgeon. Transhepatic approach and long-term treatment with methyltertiary-butyl ether are considered obligatory.

Acute Disease↗