Domuz Gribi: Durum Kuş Gribinden Tehlikeli

İnfluenza A virüslerinin evriminde korkulan gerçekleşiyor mu

Carbon and nitrogen substrate utilization in the marine bacterium Sphingopyxis alaskensis strain RB2256

Sphingopyxis alaskensis is a marine member of the Alphaproteobacteria that is adapted to heterotrophic growth under nutrient-depleted (oligotrophic) conditions. S. alaskensis strain RB2256 is an ultramicrobacterium (cell volume <0.1 mu m(3)), and has a genome size larger than that of the ultramicrobacterium 'Candidatus Pelagibacter ubique' HTCC1062 (SAR11 clade of Alphaproteobacteria): 3.35 versus 1.31 Mbp. In this study, we investigate the carbon and nitrogen metabolism of strain RB2256 using an integrated approach that combines growth and enzyme assays, proteomics and genome analysis. S. alaskensis is able to use specific amino acids and putrescine as a sole carbon and nitrogen source, and higher energy-yielding substrates such as glucose and trehalose as carbon sources. Alanine, in particular, emerges as a very important substrate in S. alaskensis metabolism. In an oligotrophic environment where competition for nutrients is intense, our data support a simplified metabolism for S. alaskensis in which the fate of certain substrates is constrained, especially at the intersections of central carbon and nitrogen metabolism, in order to ensure optimal disposition of scarce resources. This is the first investigation of central metabolism for an oligotrophic ultramicrobacterium that possesses a relatively large genome size. In contrast to the behavior so far observed for SAR11 oligotrophic bacteria, S. alaskensis shows a physiological capacity to exploit increases in ambient nutrient availability and thereby achieve high-population densities. The ISME Journal (2009) 3, 1036-1052; doi:10.1038/ismej.2009.52; published online 21 May 200

Isolation and Characterization of Dehalobacter sp Strain TeCB1 Including Identification of TcbA: A Novel Tetra-and Trichlorobenzene Reductive Dehalogenase

Dehalobacter sp. strain TeCB1 was isolated from groundwater near Sydney, Australia, that is polluted with a range of organochlorines. The isolated strain is able to grow by reductive dechlorination of 1,2,4,5-tetrachlorobenzene to 1,3- and 1,4dichlorobenzene with 1,2,4-trichlorobenzene being the intermediate daughter product. Transient production of 1,2-dichlorobenzene was detected with subsequent conversion to monochlorobenzene. The dehalogenation capability of strain TeCB1 to respire 23 alternative organochlorines was examined and shown to be limited to the use of 1,2,4,5tetrachlorobenzene and 1,2,4-trichlorobenzene. Growth on 1,2,4-trichlorobenzene resulted in the production of predominantly 1,3- and 1,4-dichlorobenzene. The inability of strain TeCB1 to grow on 1,2-dichlorobenzene indicated that the production of monochlorobenzene during growth on 1,2,4,5-tetarchlorobezene was cometabolic. The annotated genome of strain TeCB1 contained only one detectable 16S rRNA gene copy and genes for 23 full-length and one truncated Reductive Dehalogenase (RDase) homologs, five unique to strain TeCB1. Identification and functional characterization of the 1,2,4,5-tetrachlorobenzene and 1,2,4-trichlorobenzene RDase (TcbA) was achieved using native-PAGE coupled with liquid chromatography tandem mass spectrometry. Interestingly, TcbA showed higher amino acid identity with tetrachloroethene reductases PceA (95% identity) from Dehalobacter restrictus PER-K23 and Desulfitobacterium hafniense Y51 than with the only other chlorinated benzene reductase [i.e., CbrA (30% identity)] functionally characterized to date

The use of isothermal titration calorimetry for the assay of enzyme activity: Application in higher education practical classes

Determination of enzyme activity is crucial for discovery, research, and development in life sciences. The activity of enzymes is routinely determined using spectrophotometric assays that measure rates of substrate consumption or product formation. Though colorimetric-based detection systems are simple, rapid, and economical to perform, the majority of enzymes are unsuitable for this technique as their substrates/products do not absorb in the UV or visible range. This limitation can be addressed by the use of coupled-enzyme assays or artificial chromogenic substrates; however these approaches have their own drawbacks. Here, we describe a method based on the use of an isothermal titration calorimeter (ITC) to measure the heat produced or absorbed during any enzyme-catalyzed reaction. The concept of calorimetric enzyme assays was demonstrated for the determination of enzyme hexokinase activity, which cannot be monitored colorimetrically without first coupling it to another enzymatic reaction. The assay is suitable for incorporation into undergraduate laboratory classes, providing students with an appreciation for; the versatility and ease of use of ITC assays; ITC as a flexible generic method for exploring the functional characteristics of uncharacterized enzymes; an activity detection parameter suitable for enzymes that either have no straightforward colorimetric methods available or require the use of nonartificial chromogenic substrates

Complications after lumbar discectomies: A medicolegal perspective from Turkey

Lumbar discectomy is the most commonly encountered cause of lawsuits among medicolegal cases in Turkey. The evaluation of medical malpractice in Turkey has been carried out by the Supreme Council of Health under the Ministry of Health and the Institute of Forensic Medicine under the Ministry of Justice, which are all accepted as medical experts by courts of law. This study includes medicolegal review of 14 patients who had undergone discectomy during the period of 1998 to 2005 and who have been investigated and reported by the Third Special Board comprising medical experts for medical malpractices in the Institute of Forensic Medicine. Six patients had intra-abdominal large vessel injury, 6 had postoperative discitis, and 2 had wrong space intervention. The Special Board decided that the practice in 8 of the 14 cases was not within the range of medically permitted risk, and the neurosurgeon was negligent while no negligence was found to have occurred in 6 cases. The conclusion of this review was that it is important that a neurosurgeon should tell the patient that a life-threatening complication may ensue after lumbar discectomy and should fully inform the patients or the next of kin about the complications of such surgery. In case of a medical malpractice event, which is not included in the medically accepted risks by the majority of neurosurgeons, it is inevitable that the surgeon will be found negligent in the Turkish system despite the presence of an informed consent