Preparation and properties of mitochondria derived from synaptosomes

A method has been developed whereby a fraction of rat brain mitochondria (synaptic mitochondria) was isolated from synaptosomes. This brain mitochondrial fraction was compared with the fraction of "free" brain mitochondria (non-synaptic) isolated by the method of Clark & Nicklas (1970). (J. Biol. Chem. 245, 4724-4731). Both mitochondrial fractions are shown to be relatively pure, metabolically active and well coupled. 2. The oxidation of a number of substrates by synaptic and non-synaptic mitochondria was studied and compared. Of the substrates studied, pyruvate plus malate was oxidized most rapidly by both mitochondrial populations. However, the non-synaptic mitochondria oxidized glutamate plus malate almost twice as rapidly as the synaptic mitochondria. 3. The activities of certain tricarboxylic acid-cycle and related enzymes in synaptic and non-synaptic mitochondria were determined. Citrate synthase (EC 4.1.3.7), isocitrate dehydrogenase (EC 1.1.1.41) and malate dehydrogenase (EC 1.1.1.37) activities were similar in both fractions, but pyruvate dehydrogenase (EC 1.2.4.1) activity in non-synaptic mitochondria was higher than in synaptic mitochondria and glutamate dehydrogenase (EC 1.4.1.3) activity in non-synaptic mitochondria was lower than that in synaptic mitochondria. 4. Comparison of synaptic and non-synaptic mitochondria by rate-zonal separation confirmed the distinct identity of the two mitochondrial populations. The non-synaptic mitochondria had higher buoyant density and evidence was obtained to suggest that the synaptic mitochondria might be heterogeneous. 5. The results are also discussed in the light of the suggested connection between the heterogeneity of brain mitochondria and metabolic compartmentation.     

The OODB path-method generator (PMG) using access weights and precomputed access relevance

A path-method is used as a mechanism in object-oriented databases (OODBs) to retrieve or to update information relevant to one class that is not stored with that class but with some other class. A path-method is a method which traverses from one class through a chain of connections between classes and accesses information at another class. However, it is a difficult task for a casual user or even an application programmer to write path-methods to facilitate queries. This is because it might require comprehensive knowledge of many classes of the conceptual schema that are not directly involved in the query, and therefore may not even be included in a user's (incomplete) view about the contents of the database. We have developed a system, called path-method generator (PMG), which generates path-methods automatically according to a user's database-manipulating requests. The PMG offers the user one of the possible path-methods and the user verifies from his knowledge of the intended purpose of the request whether that path-method is the desired one. If the path method is rejected, then the user can utilize his now increased knowledge about the database to request (with additional parameters given) another offer from the PMG. The PMG is based on access weights attached to the connections between classes and precomputed access relevance between every pair of classes of the OODB. Specific rules for access weight assignment and algorithms for computing access relevance appeared in our previous papers [MGPF92, MGPF93, MGPF96]. In this paper, we present a variety of traversal algorithms based on access weights and precomputed access relevance. Experiments identify some of these algorithms as very successful in generating most desired path-methods. The PMG system utilizes these successful algorithms and is thus an efficient tool for aiding the user with the difficult task of querying and updating a large OODB. Received July 19, 1993 / Accepted May 16, 1997     

Technological Aspects of Orientational Strengthening of Poly(Ethylene Terephthalate). Modern Schemes for Production of High-Strength Polyester Fibres

Theoretical and technological aspects of orientational strengthening of polyester fibres are examined. High strength of polyester fibres is attained by the combination of the high molecular weight of poly(ethylene terephthalate) with stage-wise (in several stages) drawing. Current schemes for production of high-strength polyester fibres are reported.     

达芬奇效应:简便的数字视频

数字视频将引发人们与电子产品交互方式的变革。实现数字视频不但复杂,而且费时费钱。而这一切难题在达芬奇技术面前全部烟消云散。     

Rheological characterization of yellow grease and poultry fat

The rheological properties of yellow grease and poultry fat and their liquid density at 25.0°C were experimentally determined. Dynamic viscosities of these industrial recycled fat products were measured for shear rates of 0.65 to 32.34 s⁻¹ at temperatures of 15.6 to 71.1°C. The resulting measurements were fitted to a power law model to obtain values for the consistency coefficient and the flow behavior index. The data was also fit to Andrade's equation to relate viscosity to temperature. These results indicated pseudoplastic flow behavior for both products, with increasing non-Newtonian behavior at higher temperatures and shear rates.     

Experience with reduction mammaplasty following breast conservation surgery and radiation therapy

Little is known about the outcome of breast reduction in the previously radiated breast. With the increased popularity of breast conservation in the management of breast cancer, it is inevitable that more women with breast cancer who have had a breast radiated will be seeking breast reduction. Although it would be expected that reduction of the radiated breast would be more challenging and would yield less-pleasing results, it has been unclear whether reduction in the radiated breast could be safely performed without interfering with mammography and cancer surveillance. Our experience using different techniques in three patients demonstrates that such reductions can be effectively and safely done if certain principles are followed. Pedicles should be designed to be broader and shorter than usual, and breast flaps should be undermined or elevated either minimally or not at all.