Coagulase gene polymorphism of Staphylococcus aureus isolated from clinical and sub-clinical bovine mastitis in Isfahan and Chaharmahal va Bakhtiari provinces of Iran

Mastitis is a common disease in dairy cattle and is an inflammatory response of the breast tissue to bacterial attack to this tissue. Mastitis causes considerable loss to the dairy industry, among the several bacterial pathogens that can cause mastitis; Staphylococcus aureus is probably the most lethal agent because it causes chronic and deep infection in the mammary glands that is extremely difficult to cure. Several virulence factors including coagulase gene are produced by S. aureus and may contribute to its pathogenicity. This study was conducted to investigate the coagulase gene polymorphism of S. aureus isolated from clinical and sub-clinical bovine mastitis milk samples in Isfahan and Chaharmahal va Bakhtiari provinces of Iran. Amplification of the coagulase gene from 86 S. aureus strains isolates by specific primers showed 31 specimens contained 970 bp fragment, and 11 strains contained 730 bp fragment relevant to coa gene (coagulase) in PCR. After enzymatic digestion with AluI, 31 specimens contained three bands: 320, 490, and 160 bp (genotype I) and 11 specimens contained two bands: 490 and 240 bp (genotype VIII) in the RFLP

Effect of crack position on stress intensity factor in particle-reinforced metal-matrix composites

In this study, a numerical model was developed to study the effects of mechanical properties of the particle and matrix materials, the crack position (in particle/in matrix) and loading conditions (mode 1 and mixed-mode) in particle-reinforced metal-matrix composites. The finite element technique was used to calculate the stress intensity factors for crack at and near-interface. The Displacement Correlation Method was used to calculate the stress intensity factors K1 and K2. In the present model, the particle and matrix materials were modeled in linear elastic conditions. The interface crack was considered between the particle and matrix, without the presence of the interface. For near-interface crack problem, two different crack positions (in particle/in matrix) were selected. The obtained results show the key role on the stress intensity factors played by the relative elastic properties of the particle and matrix. The results also show that loading condition has an important effect on the K2 stress intensity factor and the crack deflection angle. © 2008 Elsevier Ltd. All rights reserved

Modelowanie mikromechaniczne zjawiska odpadania kryształów diamentu od kompozytowego fundamentu

Diamond debonding in composite segments used in cutting of natural stones was investigated in this study. The finite element method was used for numerical solutions, and the problem was modelled as two dimensional. The problem was investigated under linear elastic fracture conditions. Stress intensity factors and strain energy release rates were obtained. Numerical solutions were performed for different diamond sizes and diamond heights. According to the obtained results, the most effective factor for growth of the interface crack was considered to be the tangential force acting on the diamond.W pracy omówiono problem odpadania kryształów diamentu od kompozytowej matrycy narzędzi do cięcia naturalnych kamieni. Zagadnienie sformułowano dwuwymiarowo, a do uzyskania wyników symulacji numerycznych wykorzystano metodę elementów skończonych. Zjawisko badano dla warunków liniowego sprężystego pękania. Obliczono współczynniki koncentracji naprężeń oraz tempo uwalniania energii sprężystości. Symulacje przeprowadzono dla różnych wymiarów kryształów diamentu. Zgodnie z otrzymanymi rezultatami, stwierdzono, że głównym czynnikiem odpowiedzialnym za wzrost powierzchni pękania jest styczna składowa siły działającej na diament

Investigation of toxin genes in Staphylococcus aureus strains isolated in Mustafa Kemal University Hospital

Aim: The aim of this study was to investigate the presence of genes encoding staphylococcal enterotoxins (SEs), exfoliative toxins (ETAs, ETBs), and toxic shock syndrome toxin-1 (TSST-1) by polymerase chain reaction (PCR) in Staphylococcus aureus strains isolated from various clinical samples from the Mustafa Kemal University Hospital. In addition, PCR-based restriction fragment length polymorphism (RFLP) analysis of the coa gene was employed to genotype the isolates. Materials and methods: A total of 120 S. aureus strains isolated from various clinical samples (blood, wounds, urine, conjuctival swabs, and tracheal aspirate) over a 1 year period, 2007-2008, were used in this study. Results: Almost 65.8% of the isolates possessed at least one toxin gene. The genes most frequently found were seg-sei (40.8%), followed by sea (30%) and eta (19.2%). Overall, 35 toxin genotypes were observed, among which the genotypes seg-sei, sea-seg-sei, and sea-see predominated at the rate of 8.3%, 5.8%, and 5%, respectively. Four coagulase genotype patterns were observed, with molecular sizes ranging from 570 to 970 bp. Coo-based RFLP analysis revealed 7 different patterns using Conclusion: Our results have revealed that toxin genes were very prevalent among S. aureus isolates, and the toxigenic isolates were independent of the genotypes obtained by PCR-RFLP of the coa gene (P > 0.05)

Effect of combined oral contraceptive use on platelet volume in women at reproductive age

Investigation: Combined oral contraceptives use is associated with an increased risk of developing venous and arterial thromboembolic events. Platelet size, measured as mean platelet volume (MPV), is associated with platelet reactivity. Methods: Ninety-five women using oral contraceptives for contraception were investigated retrospectively. The patients' blood pressure, pulse and hematological values at application and at the sixth month were evaluated retrospectively. Results: There was no difference between the values of blood pressure (systolic and diastolic), pulse, hematological values (which contain leukocytes, platelets and mean platelet volume) at application and at the sixth month. Conclusion: We determined that using oral contraceptives for contraception did not change MPV values in young women