Lipid products formed during desaturation of [1-14C] stearyl CoA by hen liver microsomes

A number of lipid products are formed during the desaturation of stearyl CoA by hen liver microsomes. This article presents an analysis of the products formed when [1-¹⁴C] stearyl CoA is incubated with hen liver microsomes for various time periods. [1-¹⁴C] Oleyl CoA was the first radioactive unsaturated product formed. Synthesis of phospholipids containing [1-¹⁴C] oleic acid occurs only after the desaturase activity has begun to decline. The specific radioactivity of [1-¹⁴C] oleyl CoA was similar to the specific radioactivity of [1-¹⁴C] stearyl CoA at all time periods tested. The specific radioactivities of [1-¹⁴C] oleic acid and phospholipids containing [1-¹⁴C] oleic acid were much lower than that of the [1-¹⁴C] stearyl CoA.     

The differential capacitance of solid tantalum in some aqueous solutions

The differential capacitance of tantalum has been measured in a number of aqueous electrolyte solutions. The metal is generally covered with an oxide layer in solutions of simple inorganic anions and the electrode capacitance is 5–10 F cm^–2. In solutions of oxalate anions the electrode capacitance is much higher and corresponds to that expected for a clean metal in contact with an aqueous solution.     

Carotid endarterectomy for asymptomatic patients. Assessing results of a quantitative synthesis

Carotid endarterectomy (CE) surgery for asymptomatic patients remains controversial despite hundreds of published studies and recent randomized trials. Safety and efficacy are assessed using a quantitative synthesis method derived from meta-analysis and a "critical multiplist" inference approach. In addition, multivariate analyses reveal that use of a surgical shunt could further improve CE outcomes. Methods are examined for both their "confirmatory" and "exploratory" value.     

Qualitative Diagnosis of Condition Systems

A condition system is a collection of Petri nets that interact with each other and the external environment through condition signals. Some of these condition signals may be unobservable. In this paper, a system fault is defined in terms of observed behavior versus expected behavior, where the expected behavior is defined through condition system models. A diagnosis of this fault localizes the subsystem that is the source of the discrepancy between output and expected observations. We show that the structure of the interacting subsystems define a diagnostic causal model that captures the causal structure of subsystem dependencies. The diagnostic causal model can then be used to determine a set of subsystems that might be the source of a fault.     

Motor function of the proximal stomach and visceral perception in gastro-oesophageal reflux disease

Oxytocin (OT) is present in the mammalian testis and has been shown to play a role in the modulation of seminiferous tubule contractility and steroidogenesis. However, stage-specific effects of the peptide have not been previously investigated. In this study, computer-assisted analysis and time-lapse videomicrography were used to investigate basal contractility and the response to OT of seminiferous tubules at specific stages of the spermatogenic cycle. Adult rat testes were placed in fresh oxygenated DMEM F12 medium, decapsulated, and the tubules gently teased apart. Stages were identified by transillumination and a 10 mm section of tubule at each of stages IV-V, VII-VIII and XIII-I was placed in a microslide chamber and perifused with medium. After a control period of 3 h, OT (2 nM) was given for 1 h, followed by another control period of 1 h. The experiment was repeated using tubules from different rats and data were analysed to give arbitrary units of tubule contractility. Contractility was observed in all the tubules studied and the contractile activity was shown to vary depending on the stage of the spermatogenic cycle. Mean basal contractility at stages VII-VIII, the time when sperm are shed from the epithelium, was significantly lower than that at stages IV-V and XIII-I. The response of the tubules to OT was also stage-dependent, with the peptide producing the largest increases in contractile activity at stages VII-VIII and having no effect at stages IV-V. We postulate that these stage-specific differences in basal and OT-stimulated contractility may be important in co-ordinating the movement of developing germ cells towards the lumen of the seminiferous epithelium and in the process of spermiation.     

Epitaxial lead chalcogenide films: Orientation on substrates with the fluoride structure

Epitaxial films of the lead chalcogenides on (111)-oriented CaF₂, SrF₂ and BaF₂ substrates are azimuthally rotated by $\text{(2n ? 1)π}\text{3}$ relative to the substrate, e.g. (111)∥(111) but [10$\text{1}$]∥[$\text{1}$01]. It is shown that a model based on nearest and next-nearest neighbor interactions between the film and its substrate (over a sequence of five atomic (111) layers) leads to an interface structure that accounts for the experimentally observed orientation.     

Effect of Aluminum Phosphate Additions on the Crystallization and Bioactivity of Fluorrichterite Glass–Ceramics for Biomedical Applications

This study evaluated the effect of aluminum phosphate (AlPO₄) additions on the crystallization behavior and bioactivity of potassium fluorrichterite glasses and glass–ceramics. Four glass compositions with increasing amounts of AlPO₄ were melted. Mica and fluorrichterite were present in all glass–ceramics after crystallization. The microstructure consisted of platelet-shaped mica and prismatic fluorrichterite crystals. After incubation in simulated body fluid, a layer consisting of spherical-nanosized particles was present on the surface of the glasses. X-ray diffraction revealed the presence of hydroxyapatite after incubation of the glass and glass–ceramic powders. The addition of AlPO₄ promoted mica nucleation and bioactivity in K-fluorrichterite glass–ceramics.     

Effect of protein aggregation in the aqueous phase on the binding of membrane proteins to membranes

Analysis of the binding of hydrophobic peptides or proteins to membranes generally assumes that the solute is monomeric in both the aqueous phase and the membrane. Simulations were performed to examine the effect of solute self-association in the aqueous phase on the binding of monomeric solute to lipid vesicles. Aggregation lowered the initial concentration of monomeric solute, which was then maintained at a relatively constant value at the expense of the aggregated solute, as the lipid concentration was increased. The resultant binding isotherm has a more linear initial portion rather than the classic hyperbolic shape. Although this shape is diagnostic of solute self-association in the aqueous phase, various combinations of values for the membrane partition coefficient and the solute self-association constant will generate similar isotherms. Data for cytochrome b5 were analyzed and, when the self-association constant was estimated by gel filtration, a unique value for the membrane partition coefficient was obtained. Thus, to obtain a true partition coefficient the state of the solute in the aqueous phase must be known. If the concentration of the monomeric solute species in the aqueous phase can be independently determined, then, even with heterogeneous aggregates, the true partition coefficient can be obtained.