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L Nilsson

Publications and source records attributed to L Nilsson.

504 records · Page 28Linked to original sources
PubMedDate not supplied

Ab initio conformational analysis of nucleic acid components: intrinsic energetic contributions to nucleic acid structure and dynamics.

In recent years, the use of high-level ab initio calculations has allowed for the intrinsic conformational properties of nucleic acid building blocks to be revisited. This has provided new insights into the intrinsic conformational energetics of these compounds and its relationship to nucleic acids structure and dynamics. In this article we review recent developments and present new results. New data include comparison of various levels of theory on conformational properties of nucleic acid building blocks, calculations on the abasic sugar, known to occur in vivo in DNA, on the TA conformation of DNA observed in the complex with the TATA box binding protein, and on inosine. Tests of the Hartree-Fock (HF), second-order Møller-Plesset (MP2), and Density Functional Theory/Becke3, Lee, Yang and Par (DFT/B3LYP) levels of theory show the overall shape of backbone torsional energy profiles (for gamma, epsilon, and chi) to be similar for the different levels, though some systematic differences are identified between the MP2 and DFT/B3LYP profiles. The east pseudorotation energy barrier in deoxyribonucleosides is also sensitive to the level of theory, with the HF and DFT/B3LYP east barriers being significantly lower (approximately 2.5 kcal/mol) than the MP2 counterpart (approximately 4.0 kcal/mol). Additional calculations at various levels of theory suggest that the east barrier in deoxyribonucleosides is between 3.0 and 4.0 kcal/mol. In the abasic sugar, the west pseudorotation energy barrier is found to be slightly lower than the east barrier and the south pucker is favored more than in standard nucleosides. Results on the TA conformation suggest that, at the nucleoside level, this conformation is significantly destabilized relative to the global energy minimum, or relative to the A- and B-DNA conformations. Deoxyribocytosine would destabilize the TA conformation more than other bases relative to the A-DNA conformation, but not relative to the B-DNA conformation.

DNA↗
PubMedDate not supplied

Influence of frying fat on mutagenic activity in lean pork meat.

Mutagenic activity in lean pork meat fried at two different pan temperatures, 200 degrees C and 250 degrees C, with or without the addition of fat, was measured in Ames' Salmonella test on strain TA98. 9 different fats with varying chemical composition were tested. All fried meat samples were shown to be mutagenic. At the frying temperature of 200 degrees C differences between meat samples fried in different fats or without fat, respectively, were small. All meat samples fried at 250 degrees C were considerably more mutagenic than the samples fried at 200 degrees C. At 250 degrees C, the addition of fat caused a significant rise in mutagenic activity. We believe this is mainly an effect of more efficient heat transfer from the bottom of the frying-pan to the meat samples, although other factors may also contribute.

Animals↗
PubMedDate not supplied

Mutagens in larger fungi. II. The mutagenicity of commercial pickled Lactarius necator in the Salmonella assay.

In the course of an ongoing screening of larger mushrooms for the occurrence of chemical mutagens, 33 out of 48 species tested exhibited a significant direct mutagenic activity in the Salmonella/microsome assay (Sterner et al., 1982). (No mutagens requiring metabolic activation were indicated.) These findings are of some concern, since mushrooms are used extensively as food in many areas, and there are strong indications that carcinogens in food are of considerable importance in cancer aetiology (Sugimura, 1979). A recent communication by Knuutinen and von Wright (1982) on the mutagenicity of 4 Lactarius species collected in Finland prompts us to report our own results from mutagenicity tests with commercially preserved (pickled) Lactarius necator.

Basidiomycota↗
PubMedDate not supplied

Structural analysis of an anti-estradiol antibody.

An anti-estradiol antibody with improved specificity is searched for by combining steroid analog binding studies, mutant antibodies obtained from a phage-display library and structural modeling. Three-dimensional models for the anti-estradiol antibody 57-2 were constructed by comparative model building. Estradiol and analogs were docked into the combining site and molecular dynamics simulation was used to further refine this area of the protein. Cross-reactivities measured against 36 steroid analogs were used to help in the docking process and to evaluate the models. The roles of a number of residues were assessed by characterization of cross-reactivity mutants obtained from a phage display library. The cross-reactivity data and the results observed for mutants are explained by the structural model, in which the estradiol D-ring inserts deeply into the binding site and interacts with the antibody through at least one specific hydrogen bond. The binding data strongly suggest that this hydrogen bond connects the estradiol 17-hydroxyl group with the side chain of Gln H35. As expected for the binding of a small aromatic molecule, the antibody binding site contains many aromatic residues, e.g. Trp H50, H95 and L96 and Tyr L32, L49 and Phe L91.

Amino Acid Sequence↗
PubMedDate not supplied

Shelf-life of bank blood and stored plasma with special reference to coagulation factors.

Whole blood and plasma drawn into plastic bags containing citrate-phosphate-dextrose (CPD) and stored at 4 degrees C for various periods were studied for variations of coagulation factor and fibrinolytic activity. The blood was collected and processed in the conventional way. The most labile component, factor VIII coagulant activity, decreased to about 50 percent of its original value within the first 24 hours in whole blood, but thereafter, it decreased more slowly. Storage of whole blood for 6 hours at 4 degrees C had an insignificant effect on VIII coagulant activity; an even slower decrease was found for factor VIII coagulant antigen. The major fall in VIII coagulant activity occurred between 6 and 24 hours of whole blood storage. Factor VIII-related antigen remained normal for about 1 week, but on further storage showed signs of proteolytic degradation. In plasma, there was a successive decrease in VIII coagulant activity with its minimum level (about 50% decrease as compared with the original level) after 7 to 14 days of storage. All other factor VIII activities in plasma remained unchanged throughout the study. Factor V retained its activity for about 1 week in the whole blood. Factors II, VII, IX, X, XII, XIII and fibrinogen did not fall below normal during a storage period of 35 days, nor was there any indication of increased fibrinolytic activity in either whole blood or plasma. Storage of whole blood and plasma at 4 degrees C for 1 to 2 weeks seems to have relatively little effect on the levels and function of various coagulation components with the possible exception of factor VIII coagulant activity.

Antigens↗
PubMedDate not supplied

Mercaptoethanol poisoning: report of a fatal case and analytical determinations.

A suicide due to oral intake of 2-mercaptoethanol is reported. High concentrations of 2-mercaptoethanol and its metabolite 2-mercaptoacetate were found by gas chromatography in the urine and gastric content of the victim. These compounds were also identified by gas chromatography/mass spectrometry. Increased amounts of inorganic sulfate were furthermore found in the urine. Case history and autopsy findings are presented, and the metabolism of 2-mercaptoethanol is discussed.

Administration, Oral↗
PubMedDate not supplied

Influence of two blood conservation techniques (cardiotomy reservoir versus cell-saver) on biocompatibility of the heparin coated cardiopulmonary bypass circuit during coronary revascularization surgery.

Blood conservation during cardiac surgery is critically important because of the inherent risks in homologous blood transfusions. Two techniques for the intraoperative conservation of blood--retransfusion of the red cells using a cell-saver (CS), or retransfusion of the blood using a cardiotomy suction (CTR) system--were compared using biocompatibility markers, granulocyte activation, and production of oxygen-free radicals (OFR). In the CTR group, heparin coated circuits with an uncoated cardiotomy reservoir were used. For the CS group, identical heparin coated cardiopulmonary bypass (CPB) sets, without a cardiotomy reservoir but with a CS, were used. In each group, eight patients had coronary artery bypass grafting performed. The capacity of the whole blood and the granulocytes to produce OFR was estimated by a chemiluminescence, and granulocyte activation was measured as release of the granulocyte granule proteins myeloperoxidase (MPO) and lactoferrin. A significantly reduced capacity to produce OFR by the whole blood was noted at 45 minutes of CPB in the CTR group (68% +/- 17% vs 94% +/- 16% in the CS group). MPO release was higher after 3 hours (p = 0.05) and 20 hours (p < 0.05), postoperatively, in the CTR group (417 +/- 77 micrograms/L and 257 +/- 31 micrograms/L vs 246 +/- 25 micrograms/L and 164 +/- 12 micrograms/L, respectively, in the CS group). We conclude that the heparin coated CPB circuit with the uncoated cardiotomy reservoir may be less biocompatible than the identical CPB set used together with the CS.

Biocompatible Materials↗
PubMedDate not supplied

Laparoscopy versus ultrasound guided puncture for oocyte retrieval.

IVF/ET has during the last 5 years gone through a dramatic development and expansions. Since approx. 10% of the population in fertile ages has infertility problems in the Western world the demand for IVF units outside larger University hospitals with considerable resources has become urgent. To reduce costs a trend towards simplification without loss in quality has been an ambition for everyone involved. The exchange of laparoscopic techniques to simpler and cheaper sonographic methods is one step in that direction. The present review is a comparison between the various techniques for oocyte retrieval taking into consideration the principle qualitative aspects to avoid introducing a new technique which is inferior to the originally applied technique. In summary sonographic techniques seem to fullfill these quality requirements and will for such reasons in many IVF groups gradually replace laparoscopy.

Female↗