Synthesis and applications for unnatural sugar nucleotides

The synthesis and biological evaluation of carbohydrate mimetics has begun to more clearly define the diverse roles of carbohydrates in nature. Often the strategy invoves the design and synthesis of glycosyltransferase and glycosidase inhibitors both as tools to elucidate the mechanism of action of these enzymes and as potential therapeutic agents. An array of unnatural sugar nucleotides have found utility in chemo-enzymatic synthesis. The regio- and stereoselective transfer of sugars by glycosyltransferases such as b1,4-galactosyltransferase, a1,3-fucosyltransferase, a2,3- and a2, 6-sialyltransferases and N-acethylglucosaminyltransferase V has demonstrated the broad application of this approach. This review summarizes the specificity of these well-studied glycosyltransferases for both unnatural sugar donors and acceptors. This information combined with the knowledge of the mechanism of action of those enzymes is valuable in the design of potent selective glycosyltransferase inhibitors and the chemo-enzymatic synthesis of novel carbohydrate mimetics.     

Mechanical behaviour and microstructural evolution of constrained groove pressed nickel sheets

Pure nickel sheets are subjected to severe plastic deformation by constrained groove pressing technique at room temperature thereby imparting an effective plastic strain of 3.48. The evolution of mechanical behaviour with increasing number of passes revealed intensive increase in strength properties after first pass; however marginal increase is observed subsequently. Gain in ductility which is attributed to dislocation recovery is observed after third pass along with marginal drop in strength. Microstructural evolution during groove pressing of sheets is characterized by X-ray diffraction profile analysis using Williamson–Hall method. Besides the observation of strong shear texture in constrained groove pressed sheets, improvement in strain isotropy with increased straining is revealed from Williamson–Hall plots. The sub-grain/cell size estimated by analysing the diffraction profile of deformed sheets is found to be ～1390 nm after processing up to three passes. Low grain refinement efficiency observed in this process compared to other severe plastic deformation techniques at similar strain conditions is explained by the deformation characteristics and loading behaviour experienced by the sheets during constrained groove pressing.     

Roll bonding behaviour of Ti-6Al-4V sheets during pack rolling

Low density, excellent corrosion resistance, moderate strengths at high temperatures make titanium based alloys candidate materials for advanced aerospace structures. Advanced joining techniques are emulating for fabrication of complex aerospace structures. Roll bonding is one such solid state joining technique where bonding between two rough and clean surfaces is obtained under high temperature and pressure. The work horse dual phase titanium alloy Ti-6Al-4V finds extensive structural application in aerospace and space industries. In the present study, two Ti-6Al-4V sheets are stacked together and encapsulated in a mild steel can followed by evacuation and hot crimping. The pack is extensively deformed to ∼84% reduction in thickness employing conventional hot rolling mill. Partially roll bonded 0.74mm thick sheets were obtained and microstructural evolution was studied using light microscopy and scanning electron microscopy. The incompletely bonded interface was analyzed through elemental mappings by Electron Probe Micro Analyzer and compared with completely bonded region. The partially bonded region revealed the presence of aluminium oxide at the interface which possibly could have hindered complete bonding at that region. The room temperature tensile properties of as- roll bonded Ti-6Al-4V nearly approaches the base material properties.     

Prognostic value of blood lactate, base deficit, and oxygen-derived variables in an LD50 model of penetrating trauma

OBJECTIVE: To determine whether blood lactate, base deficit, or oxygen-derived hemodynamic variables correlate with morbidity and mortality rates in a clinically-relevant LD50 model of penetrating trauma. DESIGN: Prospective, controlled study. SETTING: University research laboratory. SUBJECTS: Anesthetized, mechanically-ventilated mongrel pigs (30+/-2 kg, n = 29). INTERVENTIONS: A captive bolt gun delivered a penetrating injury to the thigh, followed immediately by a 40% to 60% hemorrhage. After 1 hr, shed blood and supplemental crystalloid were administered for resuscitation. MEASUREMENTS AND MAIN RESULTS: After penetrating injury, 50.7+/-0.3% hemorrhage (range 50% to 52.5%), and a 1-hr shock period, seven of 14 animals died, compared with six of six animals after 55% to 60% hemorrhage, and 0 of nine animals after < or =47.5% hemorrhage. Only two of 13 deaths occurred during fluid resuscitation. At the LD50 hemorrhage, peak lactate concentration and base deficit were 11.2+/-0.8 mM and 9.3+/-1.5 mmol/L, respectively, and minimum mixed venous oxygen saturation, systemic oxygen delivery, and systemic oxygen consumption were 33+/-5%, 380+/-83 mL/min/kg, and 177+/-35 mL/min/kg, respectively. For comparison, baseline preinjury values were 1.6+/-0.1 mM, -6.7+/-0.6 mmol/L, 71+/-3%, 2189+/-198 mL/min/kg, and 628+/-102 mL/min/kg, respectively. Of all the variables, only lactate was significantly related to blood loss before and after fluid resuscitation in the 16 survivors. However, r2 values were relatively low (.20 to .50), which indicates that only a small fraction of the hyperiactacidemia was directly related to tissue hypoperfusion. In the whole population of survivors and nonsurvivors, both lactate and base deficit (but none of the oxygen-derived variables) correlated with blood loss. CONCLUSIONS: Arterial lactate is a stronger index of blood loss after penetrating trauma than base deficit or oxygen-derived hemodynamic variables. The reliability of arterial lactate depends on several factors, such as the time after injury, the proportion of survivors and nonsurvivors in the study population, and on factors other than tissue hypoxia.     

Strengthening of Short Shear Span Reinforced Concrete T Joists with Fiber-Reinforced Plasic Composites

In this work, the results of an experimental study conducted in a 1964-vintage building are presented. Twelve reinforced concrete (RC) T-joists strengthened with fiber-reinforced plastic (FRP) composites were loaded until failure in a short shear span configuration. Different strengthening schemes, including different FRP materials and a new FRP anchorage system, were adopted in order to compare the performance of the different installations. Carbon FRP and aramid FRP sheets in an epoxy matrix were bonded to the RC joists using the wet layup technique. All of the joists were loaded close to one end support and showed similar cracking patterns at failure. The design calculations were based on experimental results. All of the unanchored FRP strengthened beams showed failure due to peeling, while the anchored FRP strengthened members showed failure due to anchor pullout at higher load values. It was found that an increase in the amount of FRP did not result in a proportional increase in the shear capacity, as expected by design equations, but all of the beams showed a considerable increase in stiffness. The experimental results are compared with the results expected by analytical models in order to discuss the structural behavior of FRP strengthened beams tested in a real building with a short shear span. It was found that theoretical calculations resulted in nonconservative results for the tested specimens.     

Riding injuries

The aim of this study was to investigate accidents which occur in connection with horse-riding. The material was found in a data base covering 14% of all case registered in Casualty Departments in Denmark. The number of horse-riding accidents has increased by 150% from 1986 to 1996. The majority of these were girls. The age group 10-19 years accounted for 61% of the accidents. The majority of injuries occurred on falling from the horse and particularly involved the upper part of the body. Out of 1250 injuries, 24% sustained a fracture: 64% were located to the upper extremities, and 19% lower extremities. One hundred patients required hospitalization: 29 for observation for concussion; 51 for reduction of fractures and osteosynthesis; 13 for contusion. Forty-five percent of the accidents happened in a riding arena and 25% in a stable. It is concluded that the proportion of horse-riding accidents is strongly on the increase in Ribe County.     

Pre-ECT cardiology consultation

A case of multiple primary Carcinomas of the gastrointestinal tract is reported in a man presenting with Carcinomas of the rectum and oesophagus.     

Relation between intracarotid amobarbital memory asymmetry scores and hippocampal sclerosis in patients undergoing anterior temporal lobe resections

The intracarotid amobarbital procedure (IAP) is used to evaluate memory function preoperatively in candidates for anterior temporal lobe resections (ATL). We examined IAP memory asymmetry scores in 30 patients undergoing ATL (17 R, 13 L), as a function of the presence (HS+) or absence (HS-) of hippocampal sclerosis. Ictal onset zones were determined by extraoperative recording with subdural strip electrodes in all but 3 patients in whom magnetic resonance imaging (MRI) scan showed HS. MRI scans were otherwise normal. All patients were left hemisphere dominant for language except 1, in whom language was represented bilaterally. IAP memory testing involved presentation of eight subjects during anesthesia of each hemisphere, followed by recognition testing after patients recovered from amobarbital effects. A score of 1 was given for each correctly recognized object, and 0.5 was deducted for each false-positive identification. There were 16 foils. A total asymmetry score was calculated, which was positive if there was agreement between the direction of the symmetry and side of operation and negative if reversed. The mean asymmetry score for HS- (n = 8) was 0.9; that for HS+ (n = 22) was 4.1 (p < 0.01). IAP memory performance provided lateralizing information (asymmetry score > or = + or -2) in 73% of cases; among these, the lateralization was correct in 91%. Our data indicate that IAP memory asymmetry predicts both laterality of ictal onset and the presence of HS.