Percutaneous transjejunal biliary intervention: 10-year experience with access via Roux-en-Y loops

Ancylostoma duodenale is still the dominant hookworm species in the Mediterranean area, India, China and Japan. In the present study, biopsied materials were taken from the small intestine of 30 patients infected only with A. duodenale and 12 cross matched controls. The results showed some pathological changes in severely infected cases. However, normal or insignificant changes were seen in the enzymatic activity of the intestinal mucosa.     

端点安全面临重重危机 如何轻松应对

正事实上,绝大多数攻击者是经由用户及其设备进入企业的。现实情况往往是黑客跟踪一个用户,然后此用户成为帮助黑客到达数据库或用户凭据的一个管道。因此,企业不仅需要端点安全和网络安全,而且还要将不同的安全方案集成起来。安全厂商也应当听从时代的召唤,建设针对新威胁的安全方案,迎接深度安全的新时代。     

Reversible binding of chlorpromazine to brain tubulin

Isolated lamb hearts perfused at 13degrees C. with acellular perfusates developed progressive intersitital edema and a rise in vascular resistance. They did not exhbit any electrical or mechanical activity. In contrast, hearts perfused with whole fresh blood remained well preserved, had no edema or change in vascular resistance, and contracted vigorously while being perfused at 10degrees and 13degrees C. This study was designed to determine which particular component(s) of whole blood contributed to improved cardiac preservation. Isolated lamb hearts were perfused for 18 hours at 13degrees C. with plasma containing platelets and some or no red blood cells. Continuously fresh plasma was obtained from a donor animal by means of a flow-through centrifuge. Hearts perfused at 13degrees C. with fresh plasma of either low or high platelet count contracted during the initial 2 to 4 hours of the perfusion only and were as poorly preserved as hearts perfused with acellular microfiltered plasma. A hematocrit value of 2 to 5 per cent in the plasma perfusate resulted in the hearts being preserved almost as well as with fresh whole blood; they showed a forceful cardiac activity at 13degrees C., there was no edema, the vascular resistance was stable, and after rewarming they had good ventricular function. The improvement in cardiac preservation brought about by addition of a minimal amount of red blood cells suggests a specific effect of erythrocytes on the cardiac microcirculation.     

Present status of positive scintigraphic imaging of myocardial infarction

Community hospital graduate medical education programs have been judged deficient in several areas when compared with university programs. Generally community programs are smaller, they have a greater percentage of foreign house officers and unfilled house staff positions, and their graduates do less well on specialty board examinations. Difficulties may exist in offering a balanced and broad-based educational exposure. Four separate pediatric residencies in Phoenix became affiliated in 1972. The traditional deficiencies have been overcome, and a very popular and well-balanced program has ensued. Additionally, wasteful duplication has been avoided. Disadvantages have included complex scheduling and loss of continual close contact with house officers. Assigning patients to residents for continuity of care has been difficult. Experiences gained in this amalgamation may well apply to other hospitals facing similar problems. Local consortiums, such as this, fit well into university affiliated programs or statewide organizations.     

Thermostable archaeal O6-alkylguanine-DNA alkyltransferases

Archaea represent some of the most ancient organisms on earth, and they have relatively uncharacterized DNA repair processes. We now show, using an in vitro assay, that extracts of two Crenarchaeota (Sulfolobus acidocaldarius and Pyrobaculum islandicum) and two Euryarchaeota (Pyrococcus furiosus and Thermococcus litoralis) contain the DNA repair protein O6-alkylguanine-DNA alkyltransferase (ATase). The ATase activities found in the archaea were extremely thermostable, with half-lives at 80 degreesC ranging from 0.5 hr (S. acidocaldarius) to 13 hr (T. litoralis). The temperature optima of the four proteins ranged from approximately 75 to approximately 100 degreesC, although activity was seen at 37 degreesC, the temperature optimum of the Escherichia coli and human ATases. In all cases, preincubaton of extracts with a short oligonucleotide containing a single O6-methylguanine residue caused essentially complete loss of ATase activity, suggesting that the alkylphosphotriester-DNA alkyltransferase activity seen in some prokaryotes is not present in Archaea. The ATase from Pyrobaculum islandicum had an apparent molecular mass of 15 kDa, making it the smallest of these proteins so far described. In higher organisms, ATase is responsible for the repair of toxic and mutagenic O6-alkylguanine lesions in alkylated DNA. The presence of ATase in these primitive organisms therefore suggests that endogenous or exogenous exposure to agents that generate appropriate substrates in DNA may be an early event in evolution.     

Alternative measures of pesticide use

tRNA (m5U54)-methyltransferase (RUMT) catalyzes the S-adenosylmethionine-dependent methylation of uridine-54 in the T psi C-loop of all transfer RNAs in E. coli to form the 54-ribosylthymine residue. However, in all tRNA structures, residue 54 is completely buried and the question arises as to how RUMT gains access to the methylation site. A 17-mer RNA hairpin consisting of nucleotides 49-65 of the T psi-loop is a substrate for RUMT. Homonuclear NMR methods in conjunction with restrained molecular dynamics (MD) methods were used to determine the solution structure of the 17-mer T-arm fragment. The loop of the hairpin exhibits enhanced flexibility which renders the conventional NMR average structure less useful compared to the more commonly found situation where a molecule exists in predominantly one major conformation. However, when resorting to softer refinement methods such as MD with time-averaged restraints, the conflicting restraints in the loop can be satisfied much better. The dynamic structure of the T-arm is represented as an ensemble of 10 time-clusters. In all of these, U54 is completely exposed. The flexibility of the T psi-loop in solution in conjunction with extensive binding studies of RUMT with the T psi C-loop and tRNA suggest that the specificity of the RUMT/ tRNA recognition is associated with tRNA tertiary structure elements. For the methylation, RUMT would simply have to break the tertiary interactions between the D- and T-loops, leading to a melting of the T-arm structure and making U54 available for methylation.     

Evidence for a salt bridge between transmembrane segments 5 and 6 of the yeast plasma-membrane H+-ATPase

The plasma-membrane H+-ATPase of Saccharomyces cerevisiae, which belongs to the P2 subgroup of cation-transporting ATPases, is encoded by the PMA1 gene and functions physiologically to pump protons out of the cell. This study has focused on hydrophobic transmembrane segments M5 and M6 of the H+-ATPase. In particular, a conserved aspartate residue near the middle of M6 has been found to play a critical role in the structure and biogenesis of the ATPase. Site-directed mutants in which Asp-730 was replaced by an uncharged residue (Asn or Val) were abnormally sensitive to trypsin, consistent with the idea that the proteins were poorly folded, and immunofluorescence confocal microscopy showed them to be arrested in the endoplasmic reticulum. Similar defects are known to occur when either Arg-695 or His-701 in M5 is replaced by a neutral residue (Dutra, M. B., Ambesi, A., and Slayman, C. W. (1998) J. Biol. Chem. 273, 17411-17417). To search for possible charge-charge interactions between Asp-730 and Arg-695 or His-701, double mutants were constructed in which positively and negatively charged residues were swapped or eliminated. Strikingly, two of the double mutants (R695D/D730R and R695A/D730A) regained the capacity for normal biogenesis and displayed near-normal rates of ATP hydrolysis and ATP-dependent H+ pumping. These results demonstrate that neither Arg-695 nor Asp-730 is required for enzymatic activity or proton transport, but suggest that there is a salt bridge between the two residues, linking M5 and M6 of the 100-kDa polypeptide.