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Gayane Martirosian

Publications and source records attributed to Gayane Martirosian.

At least 19 recordsLinked to original sources
PubMed2006

Vacuolization of HeLa cells by a partially purified Clostridium histolyticum cytotoxin.

Clostridium histolyticum vacuolating cytotoxin was partially purified from culture broth using ammonium sulfate precipitation, gel filtration and hydrophobic interaction chromatography. The toxin caused vacuolization of HeLa cells visible under a light microscope after 2 h and distinct after 8 h. Transmission electron microscopy revealed the presence of numerous vacuoles, condensation of the mitochondrial matrix, increased cytoplasm density and increased amounts of heterochromatin. Apoptosis was not detected either by electron microscopy or by an apoptosis/necrosis discrimination assay with fluorescein-labeled annexin V and propidium iodide, or DNA fragmentation assay. Calcium ion influx was detected by flow cytometry after labeling cells with Fluo-4 AM. Vacuolation of HeLa cells by C. histolyticum cytotoxin was inhibited by bafilomycin A1, suggesting involvement of H+ -ATPase in the formation of vacuoles.

Apoptosis↗
PubMed2006

Distribution of the serine-aspartate repeat protein-encoding sdr genes among nasal-carriage and invasive Staphylococcus aureus strains.

The sdr locus was found in all 497 investigated Staphylococcus aureus strains, although in 29 strains it contained only the sdrC gene (sdrD negative, sdrE negative). The sdrC-positive, sdrD-negative, sdrE-negative gene profile was exclusive to methicillin-sensitive S. aureus (MSSA) strains (Fisher's exact test; P = 0.0005) and was not found in the strains collected from bone infections (P = 0.0019). We also found a strong association between the presence of the sdrD gene and methicillin-resistant S. aureus strains (P < 0.0001). Our findings suggest that MSSA strains with the newly uncovered sdrC-positive, sdrD-negative, sdrE-negative gene profile have a substantially decreased potential to establish bone infection.

Bacterial Proteins↗
PubMed2006

[Atopobium vaginae: characterization and association with pathogenesis of bacterial vaginosis].

Atopobium vaginae was described in 1999 by Rodriguez et al. It is a Gram-positive bacterium producing organic acids (lactic acid, acetic acid, formic acid) as a results of glucose fermentation. It was first found in vaginal swab taken from a healthy woman using 16S rRNA analysis. A. vaginae is associated with bacterial vaginosis and its consequences in upper part of women reproductive organs.

Actinobacteria↗
PubMed2006

[The influence of AMPs from HaCaT keratinocytes on some bacteria strains derived from skin changes].

The aim of this study was to evaluate antimicrobial activity of protein extracts from HaCaT cell line against bacterial strains, isolated from clinical materials, obtained from patients with clinical symptoms of acne (Propionibacterium acnes) and gas gangrene (Clostridium perfringens and Sterptococcus pyogenes). Reference strain of Staphylococcus aureus ATCC 25923 also was used. Protein extracts from cultured HaCaT cells were obtained by 3-fold freezing/defreezing cells in dry ice following by centrifugation and incubated with appropriate bacterial suspension (0.5 McFarland scale) during 6 and 24 hours. We observed time-depending and strain-depending activity of HaCaT--protein extract. Interestingly, high activity was demonstrated against strains of S. pyogenes and C. perfringens. Because of increasing bacterial resistance to antibiotics further studies in the field of antimicrobial peptides are required.

Acne Vulgaris↗
PubMed2006

[Antimicrobial peptides].

For many years, attention has been focused on adaptive immunity as the main antimicrobial defense system. The discovery of antimicrobial peptides turned this point of view. In general, these peptides act on microorganisms directly by disrupting the structure of the microbial cytoplasmatic membranes and indirectly acting on immune system. This review provides an overview of some natural antimicrobial peptides and probability of their clinical usage.

Animals↗
PubMed2005

Determination of the cytotoxic effect of Clostridium histolyticum culture supernatant on HeLa cells in the presence of protease inhibitors.

Clostridium histolyticum culture supernatant contains numerous enzymes, which exert a cytotoxic effect on host cells. This includes lethal toxin, clostripain and high-potassium-sensitive toxin. Since the number of C. histolyticum infections increased during the last several years, it seems worthwhile to evaluate whether protease inhibitors, used for the treatment of many diseases, could influence toxicity, and thus, pathogenicity of C. histolyticum. In this study we evaluated in vitro the influence of four common protease inhibitors: aprotinin, phenylmethylsulphonyl fluoride (PMSF), l-1-chloro-3-[4-tosylamido]-7-amino-2-heptanone-HCl (TLCK) and chymostatin on the toxicity of C. histolyticum supernatant towards human epithelial HeLa cells. We show that aprotinin has no effect, while PMSF, TLCK and chymostatin potentiate the cytotoxic activity of C. histolyticum, probably by hindering natural defence mechanisms of cells. In addition, PMSF and TLCK block clostripain enzymatic activity, while chymostatin leaves it intact. Elevated cytotoxicity of the supernatant is not related to the quantity of high-potassium-sensitive toxin, as was reported previously, since desalted supernatant still exerted its strong toxic effect. Our results show that addition of protease inhibitors for treating diseases complicated by concurrent C. histolyticum infection must require special attention.

Aprotinin↗
PubMed2005

Clostridium difficile in emergency room.

Clostridium difficile strains are known as etiological agents of pseudomembranous colitis (PMC), antibiotic-associated diarrhea (AAC) and colitis (AAC) and hospital-acquired infections. The aim of this study was to determine the frequency of C. difficile infection among patients in the emergency room and to compare isolated strains by phenotypic and genotypic characteristics. During a period of 11 months, 56 stool samples taken from diarrheic patients hospitalized in the emergency room of the Medical Center UC Davis and 14 environmental samples were cultured for isolation of C. difficile strains. Eighteen C. difficile strains were isolated from stool samples cultured on selective TCCCA plates and 5 strains from environmental samples using Rodac plates. Eleven toxigenic (TcdA+/TcdB+), 6 non-toxigenic (TcdA-/TcdB-) and unique toxin A-negative/toxin B-positive (TcdA-/TcdB+) C. difficile strains were detected among patients' isolates and 3 toxigenic and 2 non-toxigenic strains-among environmental samples. The majority of C. difficile-positive patients were treated previously by antibiotics. Four strains isolated from patients' fecal samples and one strain isolated from the environment demonstrated high-level resistance to erythromycin and clindamycin (MIC >256mug/mL). The results obtained by AP-PCR and PCR-ribotyping revealed genetic heterogeneity among the strains isolated from patients' fecal samples. However, similarity was observed among environmental strains and strains isolated from patients' fecal samples. Considering the importance of emergency room patients as a potential source of C. difficile strains, it appears to be important examine these patients for C. difficile before transfer to the other hospital units.

Journal Article↗
PubMed2005

Analysis of Clostridium difficile-associated diarrhea among patients hospitalized in tertiary care academic hospital.

The frequency of Clostridium difficile strains in stool samples of patients with diarrhea hospitalized in the hematology/oncology, surgery, orthopedics, transplantology ward, and emergency room of Davis Medical Center was analyzed. A total of 786 stool samples collected from patients with diarrhea and 180 samples taken from the hospital environment were cultured for C. difficile by routine methods. There were 119 strains of C. difficile isolated: 97 (12.3%) strains from patients' stools (no enteropathogen other than C. difficile was detected in these stool samples) and 22 (12.2%) strains from the hospital environment. It was confirmed that hospital environment plays an important role in transmission of C. difficile by AP-PCR and PCR ribotyping. Among 97 C. difficile strains isolated from patient' stools 25 were nontoxigenic (A-/B-), 67 were toxigenic (A+/B+), and 5 strains were toxin B-positive/toxin A-negative. Analysis of concomitant symptoms among hospitalized patients with diarrhea demonstrated significantly longer duration of diarrhea caused by nontoxigenic strains than in cases of diarrhea caused by toxigenic strains. On the other hand, among patients infected by toxigenic strains, significantly higher leukocytosis and longer duration of fever were observed. The resistance of isolated C. difficile strains to erythromycin and clindamycin indicated the possibility of transmission in the hospital strains with macrolide-lincosamide-streptogramin B resistance type.

Bacterial Proteins↗
PubMed2005

Occurrence of antibiotic resistant enterococci in clinical specimens from a pediatric hospital.

Enterococcal infection has become a major clinical problem and E. faecalis and E. faecium are the most frequently isolated species. However, the isolation of other species (E. casseliflavus, E. gallinarum, E. durans) from clinical materials was reported recently. The aim of this study was to evaluate drug resistance of 97 species of enterococci isolated from clinical specimens of Upper Silesian Health Center of Child and Mother in Katowice. Each strain was tested for susceptibility to vancomycin, teicoplanin, aminoglycosides (gentamycin and streptomycin) and synercid (quinupristine/ dalfopristine) by the E-test method. Fifty three percent of studied enterococci demonstrated high level aminoglycoside resistance (HLAR) (MIC > 1024 microg/ml). Sixty three strains of E. faecalis were sensitive to vancomycin (MIC 1-4 microg/ml), but 5 strains demonstrated low sensitivity (3 strains with MIC = 6 microg/ml and 2 strains with MIC = 24 microg/ml). All studied enterococci were sensitive to teicoplanin (MIC < 2 microg/ml). A high percentage of E. faecium (70%) resistant to synercid was demonstrated (MIC = 2-24 microg/ml). Infection control and monitoring of antibiotic sensitivity among isolated hospital strains may prevent the transmission of resistant strains in a pediatric hospital.

Adult↗
PubMed2005

[Role of cytokines and pathogen associated molecular pattern receptors in sepsis].

Sepsis is life-treating state caused by overwhelming inflammatory response to infection accompanied by disregulation of non-specific immunity mechanisms. In this review we discussed influence of Gram-positive and Gram-negative bacterial virulence factors, cytokines as well as pathogen associated molecular pattern receptors (TLR-toll like receptors, peptydoglican recognition proteins, nucleotide binding oligomerization domains, triggering receptor expressed on myeloid cells-1) on the development and course of sepsis.

Gram-Negative Bacterial Infections↗
PubMed2005

[Chlamydia trachomatis: etiopathogenesis and diagnosis of infection].

Infection of genito-urinary tract, caused by C. trachomatis are common worldwide. In countries, where screening diagnosis and effective treatment programmes were introduced decreasing level of infections and their complications were described. Because C. trachomatis is an obligate intracellular bacterium, very often infections are asymptomatic, although complications of symptomatic and asymptomatic infections are the same. Classically diagnosis of C. trachomatis infection is made based on culture in Mc Coy cells. C. trachomatis antigen is detected by DIF and EIA. Amplification technique play very important role in diagnosis of C. trachomatis infection. In this article we analysed laboratory diagnostic tools of urogenital chlamydiosis based on literature data and own experiences.

Antibodies, Bacterial↗
PubMed2005

Co-occurrence of urogenital mycoplasmas and group B streptococci with chlamydial cervicitis.

The aim of our study was to evaluate whether in women with chlamydial cervicitis urogenital mycoplasmas and group B streptococci (GBS) colonization is found more often than among women with non-chlamydial cervicitis. This study included 351 (mean age 31.7 +/- 6.82) not pregnant, menstruating, sexually active women. We confirmed a high frequency (49.3%) of C. trachomatis infection among women with cervicitis. Cervical ectopia was confirmed in 26.5% of examined women, in half of them ectopia was associated with chlamydial infection. We did not notice differences in frequency of colonization by urogenital mycoplasmas and GBS among women with chlamydial and non-chlamydial cervicitis.

Adult↗
PubMed2005

[Chlamydia trachomatis and human papillomavirus (HPV) infections in teenage sexually active girls].

OBJECTIVE: The purpose of the study was to determine the frequency of C.trachomatis and HPV infections in teenage, sexually active girls. MATERIAL AND METHODS: 48 non-pregnant, sexually active young women (between 16-19 years of age), who submitted for periodical check-up during oral contraceptive use. Patients had periodical mild pain in the lower abdominal area and increased amount of mucigenous secretion. They had their first sexual intercourse before 16 years of age, multiple partners (>3), unprotected intercourse. The direct immunofluorescence (DIF) was used for C. trachomatis antigen detection (Chlamydia Direct IF (bioMérieux, France). DNA HPV presence and oncogenic potential was assessed using hybridization method (Hybrid Capture I HPV Assay, Digene Corp. Beltsville, MD U.S.A.). RESULTS: C. trachomatis antigen was detected in 13 aut of 48 swabs (27%), presence of HPV DNA was detected in 2 teenage girls with normal cytology (4.2%). In cytological evaluation LSIL (low grade squamous intraepithelial lesions) was described in 5 cases. In 4 of them along with LSIL coexisted C. trachomatis infection.

Adolescent↗
PubMed2005

Co-infection of hamsters with toxin A or toxin B-deficient Clostridium difficile strains.

Male Syrian hamsters (Mesocricetus auratus) were used to study interactions between different toxin deficient strains of C. difficile. After sensitization with clindamycin, hamsters were intragastrically co-infected with the appropriate dilutions corresponding to 100, 1000 and 10,000 cells of four (toxin A or B-deficient) C. difficile strains (8864, P-829, W-38 and W-74). In addition, a group of hamsters was infected with C. difficile VPI 10463, a reference toxigenic strain. Colonization and mortality was observed within 48 hours in the group of hamsters infected with the reference toxigenic strain. No clinical disease was observed in the groups of hamsters co-infected with the toxin A or B-deficient strains. Re-infection of these hamsters (co-infected with toxin deficient isolates) with C. difficile VPI 10463 resulted in clinical disease and death suggesting that these strains do not confer protection against infection with a toxigenic strain. Macroscopic and microscopic observations of the cecum of re-infected hamsters demonstrated uniformly multiple large hemorrhagic areas without pseudomembranes. Hamsters infected with as few as 100-500 cells of the toxigenic strain--VPI 10463 alone demonstrated pseudomembranes and multiple hemorrhages. These results suggest that even though the toxin deficient strains did not prevent re-infection with a toxigenic strain of C. difficile, they may play a role in the histopathologic changes after re-infections in the hamster model. Further studies with a larger number of hamsters and C. difficile strains of various molecular profiles are required to better understand the interaction between these strains.

Animals↗
PubMed2005

Assessment of blood serum immunoglobulin and C-reactive protein concentrations in workers of x-ray diagnostics units.

OBJECTIVES: Workers of x-ray departments are occupationally exposed to long-term low levels of ionizing radiation. The aim of the study was to investigate the influence of occupational exposure of low-level x-ray radiation on immunoglobulin and C-reactive protein (CRP) concentrations in radiology workers. MATERIALS AND METHODS: In the study group of 41 x-ray department workers and the control group composed of 32 persons, immunoglobulins (IgM, IgG, IgA) and CRP concentrations were analyzed. The study group was subdivided by gender and smoking habit. RESULTS: A significant decrease in IgG level was found in the workers and the female subgroup. The same observation was made when smokers and nonsmokers of both groups were compared. Smoking workers showed lower concentrations of IgA than non-smokers. The remaining results of immunoglobulin and CRP concentrations did not show significant differences. CONCLUSIONS: Occupational exposure to low levels of ionizing radiation is associated with suppressive influence on the immunoglobulin production, especially IgG. In addition, smoking decreases the production of IgA in radiology workers.

Adult↗
PubMed2004

[Nanobacteria--microbiological characteristics].

We have reviewed recent publications regarding the microbiological characteristic and pathogenicity of a novel infectious agent, the mineral-forming, sterile-filterable, slow-growing Gram-negative Nanobacteria, detected in bovine/human blood, kidney cyst fluid, urine and kidney stones. According to their 16S rDNA structure, nanobacteria belong to the alpha-2 Proteobacteria, subgroup, which includes the Brucella and Bartonella species. Their cell diameter is 0.2-0.5 microm (the smallest known cell-walled bacteria). Their most remarkable characteristic is the formation of carbonate apatite crystals of neutral pH and at physiologic phosphate and calcium concentrations. The extracellular mineralization forms a hard protective shelter for these hardy microorganisms, and enables them to survive conditions of physical stress that would be lethal to most other bacterial species. The Olavi Kajander group (Finland) suggests that the apatite produced by nanobacteria may play a key role in the formation of all kidney stones, by providing a central calcium phosphate deposit around which other crystalline components can collect. Nanobacteria seems to be a causative agent of diseases related to biomineralization processes.

Animals↗