Liquid4He. II. Three-body correlations and their contribution to the binding energy and the depletion

The three-body contribution to the binding energy of liquid⁴He is calculated. The methods applied are those developed mainly by Bethe and collaborators for nuclearmatter calculations, and later modified by the author for liquid³He. Various two-body wave functions and reaction-matrix elements are calculated, as is the effective interaction or representation of the reaction matrix in coordinate space. Three-body wave functions and three-body energy contributions are then calculated or estimated. The calculations are repeated for several values of the density and for several values of the intermediate-state relative momentum between the two interacting particles. The three-body contribution to the binding energy is found to be approximately –1.3 to –1.6 K per particle. This is, however, a rather uncertain value because the results are very sensitive to the values chosen for the average relative momentum in the calculations of the effective interaction off the energy shell. Also, in parts of the calculations only theS wave is included, and it is taken to represent the effect of the total wave function. The total binding energy of liquid⁴He is estimated by adding together the contribution from separate calculations of the two-body and the three-body interaction. A self-consistent solution is obtained through the depletion of the zero-momentum state, which is also estimated. The calculations are done for two different two-body potentials, an Yntema-Schneider potential given by Brueckner and Gammel, and a Frost-Musulin potential given by Bruch and McGee. The theoretical results are –4.0 to –5.0 K for the binding energy and 44–50% for the depletion. The corresponding experimental results are –7 K and 83%, respectively, i.e., the difference is generally within a factor of 1.5–2. The agreement with experimental results is probably reasonably good (or bad) since four-body and higher order cluster terms are not included.     

The use of a pharmacophore model for identification of novel ligands for the benzodiazepine binding site of the GABAA receptor

A Catalyst pharmacophore model has been developed for the benzodiazepine site within the GABA(A) receptor complex. The model is based on a pharmacophore model originally proposed by Cook and co-workers (Drug Des. Discovery 1995, 12, 193-248) and further developed by Kahnberg et al. (J. Med. Chem. 2002, 45, 4188-4201). The Catalyst pharmacophore model has been validated by using a series of flavonoids with varying affinities for the benzodiazepine receptor and has then been used as a search query in database searching with the aim of finding novel structures which have the possibility to be modified into novel lead compounds. Five of the hits from the database searching were purchased and their affinities for the benzodiazepine site of the GABA(A) receptor were determined. Two of the compounds displayed K(i) values below 10 microM. The substance showing highest potency in-vitro displayed an affinity of 121 nM making it an interesting compound for optimization. The false positive compounds (K(i) values >10 microM affinities) have been analysed in terms of conformational energy penalties and possibilities for hydrogen bond interactions. The analysis clearly demonstrates the need for post processing of Catalyst hits.     

Chaperone‐like activity of β‐casein and its effect on residual in vitro activity of horseradish peroxidase

In this study, the residual activity horseradish peroxidase was used as a novel marker of chaperone‐like activity of β‐casein under elevated temperature. It was shown that β‐casein does affect residual activity of horseradish peroxidase (HRP) depending on the concentration and molar ratio between proteins. Incubating HRP (0.1 mg mL^?1) for 10 min at 72 °C resulted in residual activity of 59 ± 5%, while addition of 1 mg mL^?1 β‐casein resulted in increase in residual activity up to 85 ± 1%. Increased residual activity is not merely attributed to an effect of higher total protein concentration, as similar experiment with bovine serum albumin resulted in residual activity of horseradish peroxidase that was significantly lower than without any addition. The effect of β‐casein on HRP disappears when pH is below the isoelectric point of β‐casein. It was also proven by light scattering studies that β‐casein interacts with horseradish peroxidase when the temperature was increased from 25 to 70 °C whereas interactions seem to cease when temperature was lowered back to 25 °C. This study highlights how specific proteins can influence enzyme activity, which is of potential importance for various industries such as enzyme manufacturers and food industry.     

Plasma Lipid Levels of Rats Fed a Diet Containing Pork Fat as a Source of Lipids after Splenic Surgery

Experimental studies have suggested an important role of the spleen in lipid metabolism, although with controversial results. Our purpose was to analyze the effect of a nutritionally balanced (NB) diet and a diet containing pork fat (PF) as source of lipids on the lipid profile of rats submitted to splenic surgery. Sixty adult male Wistar rats were divided into six groups of 10 animals each: 1 sham-operated, NB diet; 2 sham-operated, PF diet; 3 total splenectomy (TS), NB diet; 4 TS, PF diet; 5 TS followed by splenic autotransplantation (SA), NB diet; and 6 SA, PF diet. Blood samples were collected at the beginning (D0) and after 12 weeks of the experiment (D + 12) for plasma lipid determination. Morphologic regeneration of splenic tissues was observed, with no differences between groups 5 and 6. When D + 12 plasma lipid levels were compared to D0 levels there were no differences in groups 1, 3, and 5, while in groups 2, 4, and 6 total cholesterol (TC), low density lipoprotein (LDL), very low density lipoprotein (VLDL), and triacylglycerols (TAG) increased, and high density lipoprotein (HDL) decreased. At D + 12, groups 2, 4, and 6 had lower HDL than group 3. In conclusion, regardless of the surgical procedure applied to the spleen, an NB diet maintained plasma lipid levels while a diet with PF as source of lipids changed the animals’ lipid profile.     

Nutritional quality and protein value of exotic almonds and nut from the Brazilian Savanna compared to peanut

The aim of this study was to determine the nutritional quality and protein value of the baru almond, pequi almond, and cerrado cashew nut compared to the peanut. We determined the proximate chemical composition, mineral content, and amino acid profile. A biological assay was carried out to assess the protein value, by net protein ratio (NPR), relative net protein ratio (RNPR), and protein digestibility-corrected amino acid score (PDCAAS) indexes. We found that the exotic almonds and the nut are rich in proteins (22.7-29.9 g/100 g), lipids (41.9-50.0 g/100 g), fibres (baru and pequi almonds, around 10.0 g/100 g), iron and zinc (4.3-7.4 mg/100 g). Baru almond's protein did not show deficiency in essential amino acids and lysine was the first limiting amino acid in the proteins of the pequi almond and cerrado cashew nut. The baru almond showed a RNPR of 86%, similar to that of the cerrado cashew nut (78%), but higher than that of the peanut (72%) and of the pequi almond (54%). The PDCAAS value of the baru almond (91%) was the highest and cerrado cashew nut and peanut presented similar values of this index (82%), which were higher than that of the pequi almond (55%). The baru almond has the highest protein quality, but the cerrado cashew nut and peanut are sources of good quality protein, too. We recommend the inclusion of these exotic foods in healthy diets and in food industry, and the baru almond and cerrado cashew nut as sources of complementary protein.     

Documents in Place: Demarcating Places for Collaboration in Healthcare Settings

The notion of place often connotes our understood reality populated with people, practices, meanings, and artifacts. This paper suggests that documents, whether electronic, paper-based, or set in stone, offer important insights into how people establish and maintain places for communication and coordination. Data from an ethnographic study in a large hospital system illustrates how doctors carefully craft their medical histories in various electronic record systems to demarcate specific places for their communication and coordination with specific collaborators. Such documents serve as portable places, allowing the doctors to navigate a constantly changing landscape of relevant patients, participants, times, and spaces. The documents demarcate such places by pointing out the interdependencies among particular participants, places, and times. Doctors care deeply about these documents and they play a central part not only in securing efficient communication and coordination but also in the socialization of newcomers. A study of the complex interrelationships between documents and place, therefore, offers important insights into organizational environments characterized by distributed and mobile work practices.