The most common antibiotics prescribed by dentists for dental infections in Gharyan city and neighbour regions

The type VI secretion system (T6SS) is a multi-protein complex that injects bacterial effector proteins into target cells. It is composed of a cell membrane complex anchored to a contractile bacteriophage tail-like apparatus consisting of a sharpened tube that is ejected by the contraction of a sheath against a baseplate. We present structural and biochemical studies on TssA subunits from two different T6SSs that reveal radically different quaternary structures in comparison to the dodecameric E. coli TssA that arise from differences in their C-terminal sequences. Despite this, the different TssAs retain equivalent interactions with other components of the complex and position their highly conserved N-terminal ImpA_N domain at the same radius from the centre of the sheath as a result of their distinct domain architectures, which includes additional spacer domains and highly mobile interdomain linkers. Together, these variations allow these distinct TssAs to perform a similar function in the complex.

TssA is a core component of the type VI secretion system, and phylogenetic analysis of TssA subunits from different species has suggested that these proteins fall into three distinct clades. Whilst representatives of two clades, TssA1 and TssA2, have been the subjects of investigation, no members of the third clade (TssA3) have been studied. Constructs of TssA from Burkholderia cenocepacia, a representative of clade 3, were expressed, purified and subjected to crystallization trials. Data were collected from crystals of constructs of the N-terminal and C-terminal domains. Analysis of the data from the crystals of these constructs and preliminary structure determination indicates that the C-terminal domain forms an assembly of 32 subunits in D16 symmetry, whereas the N-terminal domain is not involved in subunit assocation.

The effect of the duration of cigarette smoking on liver function

Study was to identify DNA repair gene (HexB) from S. pneumoniae in

the public databases, and using available programs to analyse and

compare the sequences between different strains. In this study, we

observe interesting polymorphisms in the sequences of HexB enzyme.

The amino acid sequences of HexB were identified from 16 strains

and differ by 1% from R6 HexB. At nucleotide level of HexB the

region 801-1000 may represent mosaic gene, as it differ by 10%. This

result suggests that the HexB proteins are highly conserved which

may indicates that these proteins perform a common essential role in repair process

ABSTRACT Computers are increasingly present in operating rooms, dental examination rooms, Intensive care unit and wards for bedside documentation. Recently they have been suspected as possible reservoirs for mi- croorganisms and provide opportunities for the transfer of pathogens to patients and ultimately leading to cause no- socomial infections. A number of studies indicate that healthcare workers may contaminate their hands by touching contaminated environmental surfaces and that contaminated hands participate to transmit the pathogen to patients. Pathogens may also be transferred directly from contaminated environmental surfaces to susceptible host in health care setting. The purpose of this study was to examine the microbial contamination of computer keyboards with potentially patho- genic microorganisms in clinical area and to postulate that computer keyboards are significant reservoirs of nosocomial pathogen. Sterile swab samples were received from 20 computer keyboards randomly from fifth year medical and fourth year dental students at AlJabal AlGharbi University and Gharian teaching hospital during a period of one month. These computer keyboards were used in clinical areas (in hospital sitting or dental practice unit). Microbes obtained from the specimens were identified to the species level on the basis of colony morphology, gram stain, biochemical test and API. Organisms isolated from the keyboards included Micrococci, Bacillus spp, Coagulase-negative staphylococci and less common isolates were Staph. aureus, Bacteroides, Flavobacterium spp, Listeria grayi, and Pseudomonas spp. Some keyboards were also contaminated with anaerobic environmental organisms. The findings of this study add evidence to support the hypothesis that these particular surfaces may serve as reservoirs of nosocomial pathogens and vector for cross transmission of infection in universities and hospital setting.

. Comparative analyses of the sequencesof DNA repair gene (Hex A) between different strains of Streptococcus pneumoniae