Effect of different amino acid diets on δ5, δ6 and δ9 desaturases

A high-protein diet with 45% calories from casein increased δ6 desaturase activity in rat-liver microsomes. High-protein diets with 45% calories from a synthetic mixture of amino acids in the same proportion as casein decreased the δ9 desaturase, slightly increased the δ5 desaturase and greatly increased δ6 desaturase activities compared with a high-carbohydrate diet. The elimination of phenylalanine and tyrosine from the synthetic mixtures of amino acids increased the δ6 desaturase activity. Massive amounts of phenylalanine or tyrosine in the diet inhibited δ6 desaturase activity. Tyrosine and phenylalanine may, by conversion to tyrosine, decrease the activity of the δ6 desaturase.     

Mapping and comparison of the B-cell epitopes recognized on the Plasmodium vivax circumsporozoite protein by immune Colombians and immunized Aotus monkeys

We present a protocol for in vitro immunization of B cells using monocyte-derived accessory cells (MoAC). MoAC are developed from human peripheral blood monocytes in culture and represent functionally competent inducers of antigen-specific immune responses. Using MoAC, we attempted to immunoselect TT-specific lymphocytes by rosetting. Adherent human MoAC were pulsed with tetanus toxoid (TT) and allowed to form clusters with autologous lymphocytes, followed by removal of non-adherent cells. After one week of culture, a specific anti-TT antibody response emerged on a low background of unspecific Ig. In comparison, cultures which had not been selected for adherent cells produced a high polyclonal background. Our results demonstrate that from peripheral blood cells, previously not a favourable source for in vitro immunization, in a majority of tests antigen-specific B cells could efficiently be immunoselected via adherence to autologous antigen-presenting cells, leading to a high-titre in vitro immunization.     

The effect of temperature on the water electrolysis reactions on nickel and nickel-based codeposits

Usually, an increase in the temperature of operation leads to a reduction in the voltage of operation of commercial water electrolyzers. The present work analyzes this effect in connection with the overpotential of the hydrogen and oxygen evolution reactions on electrodeposited nickel and some nickel-based codeposits which under normal operational conditions have shown good electrocatalytic characteristics. Results on pure nickel are also presented for comparison. A pressure chamber, adequate for electrochemical studies at high temperatures and pressures is described.     

Effects of intraoperative blood transfusion on postoperative complications and survival after orthotopic liver transplantation

BACKGROUND/AIMS: Massive blood transfusion related to the coagulation disorders occurring during the anhepatic and reperfusion phases, remains a serious problem during orthotopic liver transplantation. To analyze the influence of intraoperative blood transfusion on postoperative complications, and survival and to identify the preoperative variables associated with greater intraoperative bleeding, 100 orthotopic liver transplantations, carried out on adults, were reviewed in our center. METHODOLOGY: Patients were grouped into three categories according to intraoperative blood volume transfused; group A, 1.5 or less blood volumes transfused; group B, > 1.5 and < 3 volumes used and group C, 3 or more volumes given. RESULTS: Group C patients had a higher incidence of upper abdominal surgery (p < 0.01 between groups C and A. and p<0.05 between groups C and B); higher values of postoperative total bilirubin and SGOT, and lower prothrombin activity. Acute rejection and steroid-resistant episodes per patient occurred less commonly (p <0.01 between groups C and A) and so did chronic rejection (p <0.05 between groups C and B). Higher infection rate, and gastrointestinal and intraabdominal complication rates were also noticed in groups C and B (p < 0.01 and p < 0.05 respectively). Patient survival rates were lower in group C (p < 0.05 between groups C and A). CONCLUSIONS: It was concluded that previous upper abdominal surgery was the only preoperative factor associated with massive blood transfusion. Poor graft function during the first days after transplant, higher incidence of infections, higher incidence of gastrointestinal and intraabdominal complications, and lower rejection episodes and survival for patients receiving intraoperatively large amounts of blood can be expected.     

Tritium distribution at the crack tip of high-strength steels submitted to stress corrosion cracking

The experimental results presented in this article are the first direct evidence of hydrogen diffusion in 4120 and 4130 high-strength steels undergoing a stress corrosion cracking (SCC) test with an enhancement of the hydrogen concentration at the crack tip. The hydrogen entry is evidenced by electrochemical permeation experiments performed either at the corrosion potential or under cathodic polarization in selected microstructures. The autoradiography of tritium associated with microdensitometric measurements allows measurement of the hydrogen distribution and local concentration at the crack tip of specimens undergoing SCC in a tritiated aqueous medium. The small enhancement in the tritium concentration measured at the crack tip of the 4120 steel may be a consequence of a strong contribution of trapping sites throughout the microstructure, prevailing on the effect of the stress state on the local concentration of tritium.     

Probabilistic production costing modeled with AMPL

The work presented deals with long-term hydrogeneration optimization in integrated systems when there are no limitations on the availability of fuels for thermal units. A multicommodity network model represents stochastic hydrovariables. Uncertainty due to random inflows means that the hydrogeneration's share in production is undeterministic, and this is carefully considered by means of treatment of the load duration curve described in this paper. A suitable approximation of the expected production cost is minimized subject to multicommodity network constraints. The model was written with the AMPL language and tested with realistic cases. Simulation with many inflow sequences was used to validate the results obtained